But is there really no possibility for GSX to avoid this? GSX does know where the airplane is to correctly place jetways and vehicles so this should be no big deal.
Of course there is, but in the proper way, which is customizing their starting position.
If GSX tried to do what you are probably suggesting, that is placing vehicles depending on the airplane position and doors, the would probably always "drive right", but they will almost invariably "start wrong", since their starting position would change depending on the airplane, its parked position and its door configuration, and of course it would be very unrealistic having vehicles that change their starting position each time, when in real life they always start from preset position which are different for each gate.
That's why GSX allows you to customize the vehicles starting position at each gate, which is the only proper and realistic way to do that, because the only thing GSX knows of a parking spot is its location, heading and radius as defined in the scenery AFCAD. GSX cannot possibly know about the actual structures, ground details, it would require scanning every single polygon of the scenery, making it very heavy and slow and possibly unreliable, especially with 3rd party sceneries that might use many different methods to create objects. So, GSX is almost blind to the actual scenery, that's why there's a full customization editor.