The same way we can't have a database of gun owners.

> Are you against people taking videos in public on their cell phones?

That's literally not what's happening, though. And any suggestion that it is comes from either ignorance or lies.

I'll let you in on a little secret: there are things you and I can do that the government cannot do, and the police are the government.

I'll forgive you for thinking that the police are just private citizens.