Earlier quoted context omitted.
At minimum they should have tried for a digital attestation and not "send pictures of your official identity documents to every site" approach.
Well, they didn't take that approach. Read the actual guidance. They in no way require "send pictures of your official identity documents to every site". There are a bunch of ways (some advisable, some not) where an existing entity that knows you are an adult can extend just that -- we know they are an adult. Credit card providers know all their customers are adults, for example -- because you have to be an adult to…
That's a lot more data leakage than some central authentication for it, and PII going to more places. And it's very optimistic to assume implementations will be good faith and secure.
I'm not sure I would call the USC a mark of quality right now anyway.