Track Driving improvement/training/instruction?

[Undirection]

I’ve not done much of this but have a few questions:

The 'courses' all seem different so if I go to one it’s different from what I’ll learn on another, why?

Who trains the trainers? How do they get to be so good?

Some places have lots of trainers, are they all as good as each other? And (answering my own question potentially) is it simply that they are not but all are much better than the people they teach?

Do some trainers hire tracks/ track time to train people?