But driving requires a person to be above a certain age. They have to go through a test to prove they're competent. And there's still certain rules to follow like not being intoxicated while driving even after they have proved themselves to be competent.

And most importantly driving is a privilege that can be taken away if someone repeatedly fails to comply with the rules. So not really a rational rationale

How about "drunk driving puts others at risk and you shouldn't drive a car when you're drunk."