A lot of passenger cars have no passenger 'doors' on the sides - loungs, diners come to mind. The Athearn mode is a shortened version of the ATSF Super Chief dome lounge car. This car has no side doors as well. Passengers enter/exit the tran through the vestibule doors on the coaches or sleepers.
Even the Amtrak SuperLiner cars(diner and lounge) have no passenger entry/exit doors on the side. They do have a 'service' door on the lower level to stock the panty......
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin