I feel like because all of this is so new, we haven't had time to fully think about this stuff, and law enforcement is abusing this.
But if we take things one by one, we could see that some real restrictions could be put on the use of this technology, even in the context of existing laws.
For instance, "video surveillance is allowed because everything it sees is public."
But then you can go like "Okay, but..."
1) A regular person wouldn't remember everything it saw in public a year from now, a month from now, or even a day from now.
2) A regular person wouldn't try to build all sorts of automatic connections between various identities it sees in public over longer periods of time (say more than a few hours)
3) A regular person wouldn't be able to take punitive action with the might of the government and taking up weapons against crimes it sees happen in public (so perhaps someone like a government entity needs to be more restricted than regular people when doing certain monitoring activities, because of their inherit potential for abuse?)
Suddenly when you consider all three of these ideas, and there are probably more like them, we can realize that public surveillance doesn't have to be the "free for all" governments would like us to believe that it should be (because the more true that becomes, the more power they have against each individual, way before there's even a hint of a case against someone).