So, if the computer chip reveals that the person is of legal age, they get their drink. And by small, I mean that it should not be strong enough to kill the person, but powerful enough to render them sterile. That'll really give them something to think about. Plus, it might help the overpopulation problem. So, now that the bar issue is pretty much taken care of, let's take a look at the rest of life.
People seem to have a problem with taxes.
The American population is neatly divided into those who struggle and stress over paying taxes, and those who don't pay them at all. It's simple, really. You've heard of direct deposit. And don't worry about how much you'll get. That's simple, too.