I would imagine that most people who propose a retirement age of 70 don't have a job that requires physical labor.
This. My mom is 70 and just now retired from teaching -- so she can spend more time running her consulting company, which pays much, much better. But that is a totally different world than lifting/carrying/operating heavy equipment/etc. for 40 years.
Yes. Many of my family members worked physical labor and were wrecked by age 55.
But even intellectual jobs are hard. You never know if you will be the unlucky one with declining mental state. I know some really smart and top-notch people who start to lose their edge at 50 or 60. You can't keep the same hours, cannot remember as many things. Some of them start having to deal with illnesses which robs their ability to work. Obviously not all, but a noticeable number.
It depends entirely on the work and what it entails.
My father was an attorney and now in retirement he occasionally does some contract work, I think mostly out of boredom. The man has built a woodworking shop in the garage and built most of the furniture in the house at this point. I think he's just running out of things to do around the house so he decided to go back to law.
Law is one of those skills where a 70 year old can still be really useful. Contract law doesn't change very much year to year. I imagine most people working in their 70s will be business consultants in certain high-skill white collar professions where having a guy with 40+ years of experience is an asset and it doesn't matter how well he can pick up new skills.
Yes, my FIL is a lawyer. He was SOOOO excited to retire (in his 60s), but then cheated on his wife, got divorced, gave her the house, moved in with his girlfriend, and found himself trying to live "high on the hog" with half of his pension and SS (because ex wife got the other half).
Most of his lawyer buddies offered to throw him work now and again. I mean, he did house closings, divorces, that sort of thing. He ended up telling my hubby one day that he doesn't feel like his mental state is where he can reliably work. Thing is, I have to think that house closings are pretty boilerplate, no? He just doesn't want to work, and likes wine.
My coworkers are engineers and science PhDs. Many of them are still sharp, but some of them are not as sharp. It doesn't help that our company has had a lot of layoffs, and the amount of work to do per person has gone up exponentially. (I'm only 46 and I can't quite figure out if I'm losing my edge, or the company just keeps dumping so much work on me that I cannot keep up.)