Well I completely support the strike action. Not a teacher, but my mother was one, as was my grandfather.
My mother is 68 now. She has been retired for 5 years or so. The idea of her still teaching now is ridiculous. Yes some 68 year olds are spry and healthy. My DM is pretty well, but has very bad arthritis in one hand, and also her knees. She couldn't stand and take 7 lessons in a day. She isn't decrepit in any way. But she's a normal 68 year old with normal aches and pains.
Teaching isn't an especially well paid profession. I was earning about 28K several years ago as a town planner (also a 'profession') and I'd say I didn't work anywhere near as hard as my dc's teachers do - in terms of evenings and weekends at least.
Physically the job is more tiring than my more desk-bound work. I was also able to have a level of flexibility around my working day- starting early if I needed to leave early. Working through my lunch break if I was in late and so on. If I needed to see children's plays or if dd was ill I was able to work around it. And I worked from home for part of the week. This flexibility does not exist in teaching to the same degree. My mother would struggle into work even if feeling rotten, only to then get ill at the start of every holiday.
In order to attract the bright and motivated, who are basically the people we all want to be teaching our children, there have to be some perks. The salary is not exceptional. The pension scheme is one way of attracting men and women who could earn more in other employments, to become teachers.