Why don't more cars have sliding doors?

[Hotel India]

Having just taken delivery of a Peugot Partner Teepee (I know, I know), I have to say the sliding doors are ace. As is much of the rest of it, to be honest.

[Digby]

Had one on my funky RVR (other side of car in pic). One of the best things about it was how easy it was to collect a 50" plasma.

Opened the door, slid it in and had a friend sit in the rear seats with it perfectly upright just gently resting on his knees