Quite a few actually do require ID-scan-through-email (which is horrible). Or, they simply delegate to a third party video ident service, often in another country (because cheaper).
How exactly is the status quo not much worse than "I give you a cryptographic hash proving that I am over 18, but nothing else, and without the state knowing that this transaction happened"?
The status quo is that companies which are required by law to have this information (banks, telecommunication providers etc) do require an ID scan (and often video identification as well).
All the others don't really care and just let you register with whatever name and birthdate you want, because the ID scan method is too cumbersome and expensive to them.
I expect those to move to eID, effectively requiring people to have an eID, with no way to provide false information.
How exactly is the status quo not much worse than "I give you a cryptographic hash proving that I am over 18, but nothing else, and without the state knowing that this transaction happened"?