So on all devices I’ve played on, I always seem to get handling services go through each other. I also get the pushback car going through the terminal to get to the planes in stands z1 to z7 on IAD. If it isn’t a bug, then maybe they could add ai so the services join that little road bit which goes around the outside of most airports, as you see some driving around the outside already, but they never bring any use. So the idea is: just before the plane needs handling a message is given to the handling service to come to the certain stand, so they are there on time when they leave, they drive back onto the road and either head back to base or drive to the next aircraft
This is normal, always been there