Hmm, that is an interesting thought, but at most gas stations I've been to the pumps have about three car widths between them, at worst, two and a half. Also being on the driver side judging distance to the pump right next to you is a lot easier than doing so from the far side of the car.

I have a Mazda so I've got a driver side gas door. Personally I like it as I just step out, swipe my card, plug in the line and wait. No walking around the car necessary.

It seems to me driver side is for gas station convenience, passenger side is for road-side safety. Both are fairly minor conveniences so it seems manufacturers just pick a side and stick to it.