I've seen supes moving vehicles without wearing a seatbelt. Forgetting to tell a new driver that they need to tighten and test an e-brake, especially thoughout the day (which I'd bet $500 that very few drivers do)....absolutely a possibility.
Recently I refused to drive a pkg car because the hand brake, even when fully tightened, wouldn't hold the vehicle on a level surface in drive. Was a Sat, not a single mechanic around lol, no spare pkg cars that weren't already (partially) loaded. Told the center mgr, and he gave me a look and asked "
How would you know that the parking brake isn't working?" I shot him a look back, "Because I did this thing called a pre-trip." He rolled off without giving me instructions, so I found a supe.
Supe's plan was to have me meet an air driver, swap cars on area. "The thing is, I told you this vehicle isn't safe to drive and must be red-tagged until the parking brake is repaired, so I can't give this pkg car to ______." "Well, he's only delivering 10 stops." "And what happens if the pkg car rolls away at his 9th stop and damages property or kills someone?" Supe reluctantly called the air driver and told him to head back, help me transfer my load, and take a partly-loaded pkg car to finish his deliveries.