We already have mass surveillance, and yet we still have major crimes. It's not working, and I see no reason to believe that removing more freedom will lead to having safer streets. Why are we giving up liberty and getting nothing in return? That's an excellent reason to protest against adding more surveillance.
Our public surveillance is actually limited relative to other developed countries because it makes people here uncomfortable for cultural reasons. You’ll also note that our crime rates are pretty high, especially relative to the surveillance happy countries in East Asia.
Regardless, I’m happy to take a results oriented approach here. Does tracking license plates make it easier to catch criminals? Does it make it easier to track stolen vehicles? I suspect cities wouldn’t be signing these expensive contracts if they didn’t see any benefits.
And finally, surveillance of public spaces is not inherently at odds with personal freedoms. Your mobility is not restricted at all, your core rights have not been touched. And you are always welcome to go live in the woods off the grid.
I firmly believe that living in dense urban areas with millions of others requires a reasonably limited expectation of privacy in public spaces.