And some expect you to go in, whether you're flying or not, just in case a potential student walks through the door. And some expect you to work all the hours God sends and then some, in the summer, and forget you exist in the winter. And some are very slow payers, despite the fact they've been paid up front by the student.
They're not all like that. But you're usually self-employed, which means you'd better look after Number One...because you can guarantee no-one else will.
Instructing is a fun job, but quite often a lousy way to make a living.