I don‘t think it‘s necessarily about pay per se, but it seems like there are fewer TAs (certainly in secondary) than are needed, so all the extra work is done by teachers. The government has consistently underfunded not only schools generally but in particular SEN, meaning there are fewer SEN places and those children who should really be in an SEN school are in mainstream. This has a detrimental effect on both the kids with SEN, the kids who are almost managing but just need a little bit of extra support (but can‘t access it because the kids with more pressing needs get the assistance) as well as the other kids.
I say this as a parent of both a child with SEN (who has finally got a place in an SEN school after a long battle with the LA) and very able kids with no SEN, but who have kids in their classes who really should be somewhere that can offer them more support.
Teachers (who often don‘t have the necessary skills) are having to try and cater to all these kids, differentiate work more than would be typical and ensure that every child, regardless of their ability is coping. I know that they would have to do that anyway to a certain extent, but in reality it is more than should be typical and is just exacerbated by the lack of funding and the lack of practical support in the classroom.
It also makes it a very difficult environment to work in, coupled with kids who (backed by their parents) believe they can get away with anything. On of my DCs is in what is reported to be a really good school, and even in her classes there are kids throwing things at teachers, making them cry, constantly talking back and knowing full well there‘s little the teacher can do.
I know a few teachers who go home and then spend a lot of their evening working. In a lot of jobs, you can just switch off when you get home, but I think for a lot of teachers, this isn‘t the case.
So for me, it‘s not so much about the amount of money they bring home, it‘s more the disparity between what they are expected to do and put up with in the work environment, compared to what the government thinks they are worth. But it will backfire soon enough, many teachers are leaving the profession for their own well-being (and I don‘t blame them), but soon they will struggle to recruit enough new teachers unless they can redress working conditions, SEN needs and funding.