As a former teacher from the States (and maybe will go back to it one day, either internationally, or in another country permanently, depending on how life works out), I'd live to give my answers to some of this.

Note, I'm biased. My undergraduate degree was not in teaching but in physics. I did a masters programme in teaching to transition to becoming a teacher. I enjoyed teaching, but just ended up finding it boring teaching the same thing six times a day, so when an opportunity to do a new masters came along, I took it. I didn't leave because I got burnt out or hated it, I just wanted something a bit more challenging.

2) They are. The masters I did for teaching was a joke. I've seen high schoolers with better writing abilities than half my professors. And these are people with 'educational doctorates'. Also, this might be different at better universities, but at least in my state several are propped up by their online teaching masters (the state requires a masters) and they exist just to pump them out. If you don't get a 4.0 something is wrong. I've heard similar issues with the undergraduate programmes in the state.

3. Kids don't want to be at school. They want to be out doing kid things, which we are limiting more and more in school. They also don't want to necessarily sit and learn the stuff they're supposed to learn. It's a complex issue, but that's my take on it a lot.

4. Yep. This is, in my opinion, the number one issue facing American schools, and why private/charter (sometimes) do so much better. They can be picky about the students they take -- thus they only take those who are well behaved and who want to be there and have active parent involvement. Parent involvement is a huge predictor of school success. Until we fix that -- including the issues of poverty and not social safety net -- some schools won't improve. Kids need a safe place at home and at school if they're to truly learn and achieve what they can. Sadly, nobody talks about this issue, nor are any steps taken to change it or the culture around education. I'm from a rural area, there's people proud they dropped out and didn't get a degree and even more proud they didn't get a college one. It gets passed on.

5. Absolutely. It's incredibly difficult to teach 30+ kids at once, of various levels. Especially when they refuse to create differentiated classes. I had some classes that ran the gamut from kids who needed extra assistance and had learning disabilities to kids who would literally be in the running for valedictorian and had all accelerated classes in the subjects that had it. If I spend time on one subset of those kids, it immediately hurts the other. Now, this is a school-specific problem and lazy guidance counselors and a principal who just didn't give a shit about academically gifted students, but I had a cousin leave the school just this year because they don't care about academics because they're too worried about passing the weaker ones (not catching them up, but just making sure they can squeak by with the bare minimum). Not entirely the dehumanisation and alienation you mentioned, but I think it leads to it when the classes can't be catered towards them.

This is the one thing where I think more money could help -- get more teachers and get smaller class sizes. It'd also be nice I think to have a teacher go all four years with the students in high school, unless there's major issues, so the students get to truly know the teacher and feel like they can trust them. It could work in my state, except for science because each subject has its own certification as opposed to just one for 'math'.