> ...and no, I don't recognize a right to "privacy" that is so tentacular as to prohibit people from walking around with a camera, running some computer vision on it, and sharing the result with like-minded hobbyists doing the same thing.

Exactly. A lot of people seem to think they can have (and therefore expect) a world in which they can cover the eyes to make themselves invisible. Like little kids, they say "I have my hands on my eyes, you can't see me!". And when that fails for obvious reasons then, unlike kids, they want this magic to be enforced by law. "How dare you look at me? You're not allowed!".

It's about lowering the cost of surveillance - want to keep track of your competitors CEO or M&A team? Just set up an alert in flight radar...and it's like you have a full time team of private investigators

The hobbyists being the communication networks, tracing your phone location?

I guess this has been tried before: http://www.zeit.de/datenschutz/malte-spitz-data-retention

Well, that's the very definition of stalking

Stalking requires a target and an obsession or questionable intent. If we're stretching definitions that far, then I'll say that this is just thinking - recording inputs, correlating them and possibly acting upon them. Should we ban augmentation of thinking?

No, that's not the very definition of stalking.