I understand that a lot of local and state laws back then made it a violation to enter or exit a vehicle on the traffic side. It was a safety issue. In a lot of the old films and TV shows you see folks enter and exit only from passenger side. Even today, in most states, you can get ticketed for opening your door into a traffic lane if it is unsafe to do so. Fun fact, many early 20's cars didn't even have a driver's door.
