In some industries, you know that you'll have to stop eventually because it's too hard on your body. You can't be a construction worker until you're 80 because your body literally cannot handle it, even if you want to work for that long. The same goes for professional dancers. Some people can dance into their 70s and 80s, but that doesn't mean they can maintain the schedule and routine that Broadway dancers in their 20s and 30s do. It's just not possible.
Changing careers in your 40s because you can no longer do back-breaking work is totally different than getting hurt on the job in a way that nobody could've predicted. If you're a professional basketball player, you know that there's a possibility that you could tear your ACL during a game. If you work in an office, you do not expect that the light fixture in your office is going to fall on your head and break your neck. Both injuries can be life-ruining and devastating, but the latter isn't typical in a sedentary profession.
It's so scary to think that one injury can change the trajectory of your life. An AC unit could fall on your head while you're walking down the street, and you may never be able to work again. You could become dependent on the care of another in the blink of an eye, and there's nothing you or anyone else can do about it! The woman in this story might never be the same again after her accident, and it seems like her coworkers only care that she's a less productive employee. At least one coworker is empathetic toward her.