When there is money at stake, laws en enforcement can accomplish things that are unthinkable when it is at the expense of the common good.
Recognition of an exact pattern is computationally very easy. Examination of often subjective truths is objectively very hard?
Of course there are corner cases that are really hard, but that is no different than audio/video recognition, where a 95% solution (that also has many imperfections) gets forced on users anyway.
I'm sure that it's basically impossible. I think it's impossible even with full, proper general intelligence AI at scale, and that won't happen in my lifetime even if humanity collectively downs tools and works on nothing else.
Facebook has thrown a lot (lot lot) of resources at this, and it's clearly totally ineffective.