Like I said, it used to be done with a credit/debit card...didn't get charged (or you got charged like one cents) but the financial institution your card is connected to already verified your info, including your age.
Also, drinking, gambling, strip clubs, rent cars are all done in person. Showing your ID while you're still holding it and having one person check your D.O.B. is less risky than transmitting a copy of your drivers license online and having it in electronic form and accessible to pretty much anyone who wants it. I've had my passwords and indentity stolen several times in the past, and it wasn't from showing my ID to the bouncer at the strip club lol...