@ceilingcat - I think a lot of people make the mistake of thinking trade jobs aren't very complicated, but that just isn't true. Just because you don't need a college education to complete a job doesn't mean it's not difficult or it doesn't take special skills!
I mean, do you think you could operate and maintain all the heating and cooling equipment for the building you work in? I know I couldn't! I can definitely see that the job of boiler operator is specialized profession you need specific training for!