The question is, is it legal for you to collect everyone's emissions automatically, process them, derive conclusions from them and sell them to third parties?

The assumption that "if doing 1x of something is okay, then surely so is doing 10000x of it fully automatically" has gone unchallenged for too long. We can see the societal implications this has had so far, and it's fully logically consistent to be able to say no to that. Just because I can see you out on the street, broadcasting your visual appearance for the whole world, doesn't mean I should be allowed to record you, analyze your appearance, retain recordings of you forever, automatically track you across the places that many cameras spotted you at and then resell that data to advertising and tech corporations.

Small-scale individual recording is okay. Automated mass recording and processing without an extremely convincing reason and thorough limitations and checks should not be.