Even the bus can get interesting. Bus diesels don't do engine braking unless something's added like a Jake; some used a hydraulic retarder but those were/are unusual. Most heavy-duty automatic transmissions, especially the older ones, don't support that use - can't hold a gear (many just had reverse, neutral, drive). Older buses with drum brakes could have them fade completely away if not used right. At least RR brakes should have less "fade" because as the wheels heat up they would expand toward the brake shoes rather than away.

Brakes in general, and especially air brakes, need training and knowledge. And a mechanical department (rail or road) that maintains stuff properly. Without both, the driver is likely to have pucker moments. People whose only experience with brakes is driving a modern car, which usually is massively over-braked for its weight compared to the olde dayze with several backup systems, have no way to understand that.

Was on an old White bus (gasoline, not diesel) in SF, not even on an especially steep hill, that partially ran away with a standing load one morning when the transmission attempted to upshift and missed. Ground gears (essentially in neutral) all the way to the bottom and the smoking brakes were barely enough to allow running the stop sign and making the turn at the bottom without overturn. Stopped about a block past the stop sign on a more level section of street. Some people got off and walked the rest of the way to school (5-6 blocks) ...