Well this and a shorter work day/week so one doesn't have to chose between a social life, a healthy body, home upkeep, child care, and self care. Maybe sprinkle in some accessible and free healthcare both physical and mental. Idk, wouldn't be the first time i was wrong about something.

Exactly right. Just a bit of exercise every week is enough to get stronger muscles and no pain in back or anywhere else. At least that worked for me, and its easy to do.

Peoples bodies are rarely used for physical work if you work in some sitting down position all day, and it means you lose all muscles with time.

That sounds like a lot of work ...

Are you sure there aren't easy solutions that only involve spending money and not effort? Maybe a pill or expensive chair?