I could understand the driver's rear door not being wired for a switch if it was a 51 Frazer Utility model with the spare tire in that door and 'not supposed to open' (ie, three operating doors and the hatch) I remember there was at least one KFOCI member Utility 51 Frazer that did have the DR door that opened...not being a difficult modification to made, I suppose, since all the hardware was there anyway.
For a 4 door 51 Kaiser that makes less sense--unless it was that during the era, it was less common to exit the car on the left side, and in fact, I believe it was the law in some places. That explains why some cars only had a keyed door lock on the right hand side, as you were expected to get in and out on the right side safely out of the way of passing traffic.
Perhaps since it was legal/wasn't expected (especially for children in the rear seat?), what was the point of wiring the door??
I'd love to be proved wrong...anyone know the actual reason for this?