With computers and GPS tracking their routes and how much time they spend here and there and everywhere, FedEx drivers aren't paid to be nice and courteous. They are paid for efficiency. If the guy is behind schedule due to being trapped in traffic elsewhere, he's going to recover time by running stop signs if no poilce or traffic cameras are around to watch.
FedEx vehicle driver employees aren't anything like how they used to be decades ago after diversity kicked in.