Automatic door works only for:
- Airplanes (default or 3rd party ) that use standard variables and events for doors, which have a profile in GSX sets correctly
- 3rd party Airplanes with custom doors variables/events for which we have explicitly wrote custom code to handle automatic opening. That's PMDG case, which was easier, since the PMDG has a published SDK that allows that.
So, you should consider the special handling for PMDG as an exception, rather than the rule. Usually, it's airplane developers that do that on their own and, by default, GSX always required to open doors manually, automatic opening was added basically because default airplanes in MSFS don't have any ways for the user to open their doors.