Let's get one thing cleared up right off the bat: you can drive on the driveway. Indeed, if you'll permit me to wax philosophical for a moment, this is the very essence of drivewayness--to enable you to drive from the street to your garage. Moreover, you can park on the parkway, if you're willing to risk the wrath of the law. I don't know that this clarifies things much, but it seemed like a point worth making.

I think the crux of the issue is the dual meaning of "park."

Park in the sense of tended greenery and park in the sense of stowing your vehicle, though deriving from the same root, diverged in meaning long ago. In Old French, a parc was an enclosure. To this day a military park means an area where vehicles are stored and serviced. As early as 1812 there was a verb "to park," meaning to store one's howitzers in a military park. This carried over to carriages and ultimately to any sort of vehicle.

Our notion of landscaped parks, meanwhile, derives from the medieval practice of enclosing game preserves for the use of the aristocracy. The term was later applied to the grounds around a country estate, then to royal parks in London to which the proles were grudgingly admitted, and finally to any landscaped public grounds. The idea of enclosure is still evident in expressions like "ball park," for an enclosed playing field.

It's the same reason that night falls, but day breaks. It's the same reason we drive slow during rush hour. And it's the same reason the nurses have to wake hospital patients up to give them sleeping pills.

this is one of those thar hypotheetical questions right?

Because the people who named them were dyslexic

Cause they wanted something new for us to think about when we have nothing better to do.

Because it would make too much scence to drive on driveways and park on parkways.

The world may never know.

A parkway is a road with a lot of trees; it looks like a park. Although I think this is a pretty lame characterization! You drive into the driveway in order to park your car, so technically the name is applicable. Not too much of a mystery.

Because, on my way to and from work in rush hour, I do more parking than driving on the parkway than I do on the driveway.

Because if we drive on a driveway, and park on a parkway, we would always be saying park and drive one too many times.