To begin with: I'm not at all sure that I like Flock (or similar services). Nor am I sure that the data they collect should be accessible to the public, or to government and law enforcement agencies without warrant. I'm just point out that the question is not black and white. You seem to see the question as either completely black or white, and that is a dangerous over-simplification.
The example you provided does nothing to change my mind. Let's clarify here what you're offering as a trade off. In order to make the job of finding some people guilty in what are somewhat rare circumstances in spite of all the other tools already available to police which aren't godlike omniscience into viewing every moment of every single person's life you're willing to sacrifice privacy entirely as a concept?
And now some more detailed criticism of your post: Being able to see and record what happens in public is not "godlike omniscience into viewing ever moment of every single person's life". For example, I'm sitting in the living room right now, and I'm 100% sure no Flock camera or other such thing can see me, or know what I'm doing. Your exaggeration makes your argument quite invalid.
Next, "sacrifice privacy entirely" is also an exaggeration. When I'm out in public (like driving or walking on a public road, where anyone can see me and recognize my car or my face) is not "privacy". And that "anyone" includes literally anyone, also government employees and agencies. It seems insane to me to make a set of laws or rules that say that when I'm out in public, only my friends and neighbors are allowed to see me, but not anyone who works for the government.
By the way, if you want to know what I'm doing in the afore-mentioned living room: Typing a forum post responding to you. Want to know what I did until a few minutes ago? I was on the phone with the IRS, to figure out what ever happened to one of my tax returns which is taking too long to process. So indeed, the US government knows EXACTLY what I was doing a little while ago. But I'm all in favor of putting firewalls in there: Just because a friendly federal IRS staffer knows that I'm calling him at 10:35 on a Thursday, doesn't imply that the local county building inspector needs to also know that the ceiling fan in the living room I'm sitting in was installed without permits. Privacy is complex and multi-faceted.
Ensuring Bob's conviction(why can't they gather enough data to get that conviction without all this additional evidence like they have been for hundreds of years now?)
Because a lot of criminals have not been caught, or have had to be not convicted, because evidence is objectively hard to gather. Real-world example: A former neighbor hit their spouse with a 2x4, and then threatened their spouse by pointing a loaded gun at their head. I know both spouses and have talked with them, the head injury and treatment have been documented in civil court filings years afterwards, so I'm 100% sure the facts are correct. Yet the aggressor spouse was not convicted, because the victim spouse refused to testify, leaving the DA no choice but to drop the case. They got their guns back (had to turn them into an FFL when one was arrested for felony ADW/GBI). This is an example of a case where more evidence would be a wonderful thing. Today the clearance rate for murder is roughly one half. The fact that we've been unable to convict roughly half of all murderers, for hundreds of years, is an embarrassment. Not an accomplishment.
(And to be honest, the above example has nothing to do with Flock cameras: the crime occurred in their house, where Flock etc. don't reach, for good reasons.)
I'll go even further: ALPRs like Flock are not only justified by eventually catching murderers and domestic abusers. That is the rare but high payoff example, the tip of the iceberg. They can also be justified by many other things. For example, real-time tracking of people fleeing crime scenes (many examples of that have been published). Or tracking low-level car theft. As a real-world example: Somewhat near our house is a known place where a "chop shop" operates (they take stolen cars, part them out, and sell bits as spare parts, or re-weld the bits into vehicles whose origin is hard to establish and sell them on the black used car market). The folks operating the chop shop are criminals in all respect, associated with a handful of serious crimes (ranging from murder to arson to rape), and a whole lot of minor or lifestyle crimes (like causing a forest fire roughly 3 times per year on average), and being involved with drug distribution. I've had meaningful discussions with the sheriff's deputies who work the area, and they say: What can we do? We go in there, and we find a dozen stolen cars dumped in the creek. We talk to the car shop that operates there, and they play dumb and claim to have no idea how it got there, and we can't catch them in the act of driving it or receiving it. Wouldn't it be wonderful if the sheriff could easily get footage of the lady who operates the chop shop (with her distinctive hair style) being seen on the big county highway driving that exact car?
Also don't forget that private car repo companies are legally operating license plate readers, independent of Flock, Motorola, and Palantir. It's good for their business if they can find more people not doing car payments and repossess those. Is it good for society if they do? Probably, but we also know that repo agents and debt collectors are among the most troubling business in operating illegally and brutally, and need a lot more control and supervision. Again, the 4A doesn't help at all here (they are not a government entity, and have every right to see and remember things). But they are probably more worrisome than governmental use of Flock, since they can deal with the data under the table. At least Flock won't sell their data to the dark web, since if they got caught, they could kiss their lucrative government business good-bye.
But, as I keep repeating: We need to find a way to both accomplish better law enforcement, and prevent abuses, both by government (including LE) and by private parties.
isn't worth the cost of imprisoning our entire society in a state surveillance machine. You're ONE bad election away and one bar removed from what constitutes a crime in the eyes of the state from automated imprisonment of any and all ideological adversaries. TODAYS implementation is already exceeding the worst China can accomplish.
The comparison with China is insane. We are very far away from that.
And the guard against "one bad election" (which is indeed a worry) is to install a culture of respect for the law and for rights. Artificially hobbling the capabilities of government because it MIGHT abuse it tends to not work, because a sufficiently crooked government will simply ignore the artificial limitations. See the example above of ICE (an IMMIGRATION! agency) trying to get a complete database of all voting in the US ... that is a clear abuse of power.
Remember the old saying: The internet treats censorship as a malfunction and routes around it. If we make it so the NSA can't buy license plate reader data from Flock, they will get it elsewhere. We're better off making sure that Flock exists, thrives, is open about its business, and operates within the restraints of the law (and at this point in the discussion, we don't know what those restraints should be, as both sides have good arguments). I want to be able to see Flock's quarterly report, and have broken down in their income statement how much of their revenue was from the federal government, state government, local government (those will be most LE agencies), and foreign governments. And then be able to cross-compare those numbers against the (partially published) budgets of these agencies. Sunlight is good.
This discussion is a lot like the question many engineers face: Should I work for weapons companies (which today includes most of computing)? It's ethically troubling to build things that kill people. But is it ethically troubling to build things that kill bad people? Then, who is bad? Well, that tends to change. For example, Russia and Russians alternate between good and bad roughly every decade. And if I choose to not work on armaments, that probably just means that someone else who has fewer moral compunctions or is more easily bribed will do it. The historiography of Los Alamos is rife with these debates, and the answer is very much not black and white.