I don't have much experience in jobs like those, but a family member who jumped between whole different professions for years does. He always got bored of them because, at least according to him, all of them had one failing: you learn everything you need in a couple of months or so, then it's pretty much just getting better at doing those things repeatedly.

Eventually he tried out programming and found there's no real end to the amount of things to learn. It was the only job he found that he wouldn't get bored on. He only eventually left because of bad bosses.

I think that might be the factor that makes it hard vs easy compared to others - that for a lot of people, continual learning (which they thought they'd left behind when they finished school) is why it might be harder than the other jobs ones you listed. Though I know I'd find those ones harder for other different reasons.