The problem is that the services are asking for age verification, but to do that, you need to supply them personal information, and the way the information is handled is opaque. You’re handing highly sensitive information to a private company that, more often than not, cannot be trusted to handle that information responsibly for the singular purpose they’re tasked with.

One solution would be an official government service which supplies this information and nothing else. We have “strong identification service” in Finland, they supply your identifying information to government services and businesses that need to have the actual information on record, while you see which information gets shared. There’s no technical reason this service couldn’t just supply “Is this person 18+? Yes/No” and absolutely nothing else, even anything tying this person to any identifier.

Actually, if age verification would become a legal requirement, I’d expect the technical side to be exactly that. I frankly can’t believe the UK half-assed this stuff and went “whatever, let private providers use whatever voodoo they can come up with to make age verification happen”.