You have absolutely no idea what it's like to be a bus driver do you?.
I used to know a 266 driver, know a guy who is a mechanic at another bus company.
They cut corners like mad to make more money anyway they can just like any other company.
The drivers are treated like crap, there are no set times you could be driving a night bus one day and a day time bus the next.
Trains are all the same on the line, the drivers know the trains well, bus drivers get moved from route to route all the time and from bus to bus, since TFL don't make there own all single deckers and double deckers are different made by Mercedes, Volvo, ADL etc, all different ages, all different models.
it's not the same as trains at all, tube trains are all the same on each line with very little changes with newer models, they are on a set track, a train driver can never get lost, never go on a unfamiliar diversion, visibility at different times of day, other traffic etc all simply not a factor.
Don't compare buses to trains compare them to cars/lorries and as we know there are many accidents on the road every day for many many reasons.
And never sit at the back of a Volvo bus made in the last 5 years, they are fire hazards thanks to TFL taking a load of safety mechanisms out of them to fit there precious CCTV equipment in.