As you might guess from my user name, I used to drive buses for a living. I loved it for a while, it was a bit like being your own boss.
I left when I was spat on twice and was told I was still expected to carry the passengers who had spat on me. It was " part of the job"according to my manager. I never did carry those passengers again mind.
Most people are fine, some are great, but a significant % are just awful, perhaps 5%?
But if you carry 300 people in an average day that means you have to deal with 15 awful people. A busy day could be 500 passengers.
People smoking on the bus, getting on with their money in their mouth ( yes ,really, spit on their money in the cash tray) ,trying to avoid paying, abusing you for reasons you cannot in any way be blamed for.
This combined with zero support is why bus companies struggle to recruit and retain staff, the big companies are dreadful employers.