Jeanie asked/commented:

WHY don't they open the door on the pavement side and lean across ? Is it that difficult ?

I think you need to go back to when the driver and offspring got on board.

It's convenient and natural enough to approach from the driver's side, place the brat in the back seat, then move aside just a step or so to the driver's door to assume the wheel. When mommy (or daddy; got to be PC here) parks, of course Junior needs to be retrieved from that same side, which in parallel parking is going to be the traffic side of the car. Leaning across the width of the car to reclaim the sprat is a pain in the neck.

Q.E.D.

Dave Oesterreich