Big companies' data collection is on the whole quite subtle, and they like it that way. Google will suck up tons of data, digest it, and use it to throw ads at you. But it doesn't really occur to anybody that Google might be interested in looking for people picking their nose in front of their phone's camera, and making a compilation of that to present as "art". If anything of the sort happened, Google would make sure to make an example of whatever rogue employee did that. They like their data collection to be obscure and harmless looking. That's not to say that it is harmless, but finding problems with what Google is doing takes at least a bit of intellectual thought.

Meanwhile, an artist secretly recording people is almost certain to have some sort of quirky agenda that's going to immediately turn a large amount of people off, even if it's ultimately silly and non-consequential.