It's a very fair point, I have never seen a profession that complains so bitterly about their working conditions as teachers do. They complain a LOT.
But part of it is that a lot of people have negative things to say about them, it is unfortunate because people are nuts when it comes to their own children, and I know I was too.
ALL loving parents are unreasonable. All of them. When it comes to their own kids, some are really batshit bonkers, and some just a bit one sided but yes ALL of them, and if you think you are not one of them, you're probably the one everybody talks about 😅
What that means though is that teachers can never win and there is a lot of negativity around them, even if they are basically good at their job. And unlike a welder, there's no simple straightforward criteria to judge them from, it's all feelings based. One parent loves the teacher because Jenny is happy and flourishing, one hates the very same teacher because she feels Johnny doesn't get enough "whatever".
And in the same vein, what works for Jenny might not work at all for Johnny, so they have to be really flexible in their approach. These days they are allowed no tools of discipline except "please stop that, he doesn't like it". Even if a child is smashing up the classroom, the whole class is moved instead of the child who is being violent. And parents basically live in the school these days, even 20 years ago there was a clear line between teachers and parents, unfortunately all this "volunteering" in the school has given parents the idea that they have the right to interfere at all times.
But by the same token, teachers are also often massively overstepping and really do think they have the right to lecture kids on lifestyle choices, sexuality and have embraced the silly "Bring your whole self to work" theory to an alarming degree.
I think it's a combination of a lot of things. It is a stressful job emotionally, some of that is the teachers' doing some of it is pretty ridiculous expectations that they should be nurses, counsellors, perfect saints AND teachers all in one bundle.
It is not, generally, a stressful job physically though and the paid months off every year certainly helps.
We need a completely different education system from the ground up and that's unlikely to happen. If my kids were young again now, I'd home school them or go to a tiny rural town with a small classroom and a community which generally agreed on discipline and teaching methods.
So you're right and wrong, it is NOT physically exhausting, but it can be emotionally exhaustsing for all sorts of different reasons.