What makes a driver’s license useful as ID is that you need it to drive, meaning that people will keep close tabs on theirs, giving rise to a presumption that if you have it, it’s probably yours. (And if you lose yours, you’ll report it lost, which would show up in the computer if anyone checked — not that they do — so you can get a new one.) An expired license, on the other hand, is just trash, and could be recovered from a dumpster and used with its proper owner none the wiser.
But, you know, nobody checks that. I’ve been to the White House several times (pre-9/11) and nobody ever looked at the back of the license — even though if you just look at the front, it shows an expiration date that’s well in the past. The only person who’s ever flipped it over to check for the renewal sticker on the back was the cashier at a convenience market where I was buying beer. Give that guy Tom Ridge’s job!
I hope that security at the White House is better now, but I don’t think it’s improved all that much elsewhere.