The onus is on the organizations spying on the public and the Govt. for letting them do it.
It's one thing to snap a frame of a license plate on a freeway that the entire city uses. It's another to get a positive face detection of one kid out of a whole city, who is probably wearing a hood and staring at the ground, while walking down quiet neighborhood streets on a random side of the road under tree cover for 80% of the time. Gait is even harder.
Plus everyone carries a tracking device in their pocket regardless of mode of transport anyway (increasingly becoming the best or only way to get tickets)