If verifying people is hard and so a company chooses to take the easy route of not bothering and therefore attract lots of customers who do illegal things, surely in any world that's at the very least knowingly facilitating illegal conduct? There are a lot of platforms that do far more than Block to verify people -- Block absolutely could do the same if they wanted to.
This is what Block do: https://www.youtube.com/watch?v=J2uhWTFvug8