Earlier quoted context omitted.
The case you linked isn't about the government filming people in public, though. Carpenter vs. US was a case about the government demanding private information about users' locations from cell service providers. By comparison, the 9th circuit concluded that the plain view doctrine means electronic license plate readers are legal : https://cdn.ca9.uscourts.gov/datastore/opinions/2020/05/04/1... An officer doesn't need…
Of course that's a fair interpretation, I am saying there's some tension between mass surveillance and the fourth just because its "done in public" doesn't mean it automatically escapes scrutiny now or going forward.
I find a lot of people fail to realize this, both in regards to surveillance and otherwise. Recently in my city there was a big uproar about a nudist beach that was at risk of having nudity prohibited. So a bunch of nudists went out and paraded around the beach while disrobed, some of them bringing their children with them. People sailed by and photographed many of the nudists, and put their images online. Many alleged that must be a violation of some privacy law, but no, the law in Washington (and most, perhaps all, of the US) is quite clear: if you're in public, you can be filmed and photographed. If you don't want to be filmed nude, don't go walking around naked in public.
Regardless, back to the topic at hand, the fact that Flock cameras a in public spaces does in fact mean that there's no requirement to get a warrant to use them.