> and this work is really backbreaking.

it is still physical work, but not as hard as you claim. Modern car plants aren't sweat-shops.

I've worked at a modern car plant, and it's definitely hard work, to the extent of being very painful at the end of the day at first when you're not used to it. It does take its toll, and it's not something you can do for decades unless you are exceptionally healthy.

There's a reason the staff is mostly young, and it's not because everyone goes into management ten years into the job.