I just watched High Sierra (1941) and the driver would often get in and out of the passenger-side door.
My GF, who is an old-movie nut said that it is common in the old movies, but we have no idea why. Why? 
Just a WAG, but the passenger door is where the camera was pointed.
Previous thread, which may or may not be of any help.
To start with, it was much easier with bench seats and no center consoles. So it would be pretty quick to just slide over rather than walk around the car.
Sorry for the nitpick, but **aka **means “also known as.” I think you mean à la, which is French for, roughly, “in the manner of.”
One possibility is that it was ingrained that drivers not to go round to streetside and open a door into traffic, but I have no idea whether that was really true for the period in question.