Just because I know the starting point should be on a vehicle parking place, I added the ADE plan of EHEH at the end of my recording to show you the presence of this vehicle parking place, very near Gate 3 on which the airplane is parked. A vehicle path is connecting this parking place to the main vehicle path. Furthermore EHEH has 17 parking places (the green circles) so in my opinion there should be no reason to use a random node as a starting point. Maybe you can check it out for yourself why GSX nevertheless is using a random location at this airport.
As I've said, GSX will use a random (not really "random", it will start from a random parking, but not too far away AND it will be on a taxiway/apron path) only as a 3rd choice, if it cannot find either a Vehicle Parking or a Fuel parking within the specified parameters. Of course, the Fuel truck will use a Fuel parking 1st, a Vehicle parking 2nd, and a random parking as a 3rd choice, the other vehicles will reverse 1 and 2.
So, what really matters here, are the "specified parameters".
As I've said in my previous post, the chosen parking shouldn't be too far away, in order to not force users to wait too long for service, because the airport wasn't designed realistically enough. In this case, the maximum distance in GSX has always been 500 meters at most, but there's also a *minimum* distance ( 100 mt. ), in order not to have the vehicles being spawned right beside you, which would probably result in awkward path calculations.
So, in this case, if you were at G3, GSX skipped the Vehicle parking, because it was just NEXT to you (Parking 10 in FSX), there wasn't another one, and the Fuel parking was too far away, so it reverted to the random choice.
However, I checked the real airport on Google maps, and you can see the vehicles are parked in the parkings listed as Parking 7, 8 and 9 in FSX: these are NOT GA parkings, as the default AFCAD assumes, they are Vehicle parkings. And, what is listed as Parking 6 in FSX, should be the real Fuel parking spot instead of the one mistakenly placed in the military apron.
So, had the AFCAD been made realistically, you wouldn't have any of these issues, and the vehicles would start on their proper locations.
However, I see we might increase a bit the 500 meters distance, perhaps setting to 1000, and increase the one for the Fuel truck too. This will possibly result in an increase in the time needed to wait for the vehicles to arrive, but at least users won't be mislead thinking GSX has a problem.
However, I foresee reports of "why vehicles takes longer to arrive with the last update ?" because, as usual, when you are trying to model a realistic behavior, over a set of data that is not guaranteed to be realistic (default airports, even if they have no serious mistakes, are hardly realistic), you must do some compromise.