PAM drivers?

Probably because they dont get paid enough. Start at .30 per mile and .35 cpm after a few months. While everyone else is making at least .45 bare minimum.
Also PAM trucks are slow as hell. Max out between 62-64 depending on the truck.
Also PAM trailers are generally in really bad condition. Oftentimes drivers will be stuck once or twice a week waiting on repairs because something broke on their trailers.
Also PAM doesn't give that many miles, its common to be under 2000 miles if you're not on dedicated route. And that's a even more severe issue because the CPM is so low.

Its a snowball effect.. lot of waiting for repair/loads , low CPM , low miles, slow truck, all combine for an underwhelming experience.

Most PAM drivers are just there b/c PAM paid for their truck school and many leave even before their 1 year contract is up because they get fed up with the low pay .