Hi,
There are a number of airports where the choice of ground handling firms is a bit "surprising". For instance: parked at JFK (using the FSDT JFKv2 scenery), Terminal 4, the choice is only among several versions of "Continental". Why not Delta? There are DL-coloured ground equipments in GSX, so why not offered at JFK?
I think I had a similar issue at CYUL, where Air Canada was not offered. And a couple of others I don't recall.
What drives which ground handling firms are offered for selection at a certain airport?