Yeah, it's more about the future. Maybe in a year or three, you'll be able to write a website that does age verification using a standard web API, without processing any identity documents yourself, and expect it to work.
And sometimes kids will put fake ID's on their phones, or borrow a phone, but that's not your problem.
And sometimes kids will put fake ID's on their phones, or borrow a phone, but that's not your problem.