I wouldn't play down anyone else's job for being hard, that sounds very unfair. Where I live, people commute up to London super early and come back late, and no I wouldn't swap teaching locally for doing that sort of job. Or doing long shifts in a hospital.
It's what people don't know or see working in a classroom. I'm primary so this will be different to secondary. My experience is teaching the youngest so reception and year 1... x 30. So you have the expectations of the school, head, SLT, curriculum, ofsted, etc to meet. Plus... Observations. Staff meetings. Performance management meetings. Planning with year group. Parents evenings. School performances. Being on top of marking and classroom presentation. Actually delivering the lessons and making them interesting/fun. Subject responsibility. All of that is pretty standard and part of the job. However, you then throw in THE UNPREDICTABLE CHILDREN (haha!)...
This could mean a day where someone walks fox poo through the classroom on their way into school so even before the register starts, a shoe check gets underway.
A child comes in saying that their parent hit them last night - instant safeguarding situation.
A child wants to escape from the classroom or refuses to come into the classroom, shouting and screaming.
A sickness bug could be going round. I've had days where children have gone down like flies but because they don't always say anything when they're little, they just throw up in the classroom and the others step in it!! Poor caretakers are the heroes there.
Then there's children with any medical needs to consider, remembering to administer meds during the day or any issues around toileting.
Dealing with playground behaviour and incidents. In my first term teaching, one of my boys was kicked in the privates by a boy from a different class, and he'd recently been circumcised!! Horrific!
School trips. Constantly head counting and making sure everyone's safe and well, as well as having fun. They age me by about 10 years everytime, haha.
Then ofsted calls!! Yay!!
Even after all those things, I wouldn't say teaching is harder than any other job, but my goodness it really does throw some crazy stuff up. I've had days where I've been on brink of rocking in the corner, haha! But non teachers or parents don't see all those things.
So maybe those moaning teachers might have some good reason to have a moan sometimes. Just saying. 