Isn't that because they're expected to meet insane delivery schedules with severe consequences for their pay if they can't make them?

I assume that is part of it. But it doesn't explain their inability to back up well or navigate driveways.

I have also wondered if the better drivers have already found jobs with UPS and FedEx since they pay much better.

They never seem to be in a huge hurry when on foot.

No joking, just this morning outside my house in a residential neighborhood it’s raining heavily and a fully loaded prime van is gunning it and peeling out and fish tailing. I thought the driver was gonna crash for sure!