Well I'm late to the party here, I think (WOW you lot) but kids can have credit cards or debit cards if it's tied to an adult. I got my kid one the minute he turned 16 and it was tied to my account though. So, I think Banks do keep track of your age and whatnot, and etc.
I have NO CLUE which is the best, cheapest or any other way to do age verification, but I'm not so freaky about the last 4 of my social or DL or WHATEVER. I have found the "check my bank statements monthly and also not freak out" to be of use. I'm sure too that different companies do it differently depending on WHAT sort of like, payment method you choose.
I think a lot of this is just start up headaches from vendors getting going with the age verification thing and I believe it can be verified without said info "SS and DL" but maybe some are freaked out and going over the top and perhaps at some point it will settle down. I do not fret, although it should be noted upfront that age verification should take place and etc. because it just... should.
Mainly though I don't freak out and would rather see it in place (obviously as least burdensome as possible, which will not always be the case) but I'd rather HAVE it, especially if it's a compliance issue.
Fortunately there are lots of vendors and if you do not care for one, go to another and etc. Etc.
Anna