Despite what the tech companies say, there are absolutely techniques for identifying the sources of their data, and there are absolutely techniques for good faith data removal upon request. I know this, because I've worked on such projects before on some of the less major tech companies that make some effort to abide by European laws.
The trick is, it costs money, and the economics shift such that one must eventually begin to do things like audit and curate. The shape and size of your business, plus how you address your markets, gains nuance that doesn't work when your entire business model is smooth, mindless amotirizing of other people's data.
But I don't envy these tech companies, or the increasing absurd stories they must tell to hide the truth. A handsome sword hangs above their heads.