That's not obviously a GSX and, of course it has been discussed many times on the forum.
GSX always tries to be proper and realistic so, it will use, by preference, vehicle paths in the AFCAD and it will try, by preference, to start vehicles not starting at your parking in a parking of the vehicle type, and both are supposed to be defined in the AFCAD.
There IS a reason in the real world why dedicated vehicle paths and dedicated vehicle parkings exists: to prevent clashing of vehicles and taxiing airplanes so, for this reason, GSX will always try to use vehicle parkings and vehicle taxipath, even if they are the longer route, and will use other parkings and regular taxiways only as a last resort.
If the airport AFCAD is made realistically, with vehicle parkings placed close to the terminal they are supposed to serve, and with proper vehicle path that can reach every parking spot, the GSX vehicles will do similar paths as in real life.
But if the AFCAD of the scenery you use hasn't enough of them or they are far away from the terminal or (even worse) there are not vehicle paths/parkings at all, this will of course cause GSX vehicles taking "strange" routes, trying to NOT use taxiways (if possible).