But generally, if the FBI believes it has a car it wants to follow, I'd like them to be able to do that as effectively, cheaply, and safely as possible.
I don't see that great a difference between my Internet traffic or phone logs and my daily whereabouts (i.e. my travel traffic and my physical location logs).
Good point about the debasing of saying 'yes' to things; it might end up like the permission system in Windows 7 where you get asked for permission for damn near everything to the point one starts clicking "OK" without thinking.
But having zero friction for trailing anyone, anytime, is also a problem.
I think someone else hit the nail on the head elsewhere when they said that they wouldn't be comfortable with their neighbors doing this. I think that's relevant, because it exposes that normal people do see a privacy interest in having someone follow you around, whatever the law may currently say about the existence or non-existence thereof. Maybe it's not a reasonable expectation, but that doesn't seem right to me, even if our privacy is steadily decreasing.