Sure, but that is true for ever job then. An unknown and hidden confounding factor explaining job choice and the problems of the job can always exist.
Police officer or fire fighter aren't actually dangerous. It is simply that people who are more likely to make bad decisions that get them killed also are those that choose to be police officer or fire fighters.
Burnout does not affect teachers with higher probability than it affects hairdressers. It is because people who get burnouts are also the people who choose to be teachers.