Indeed, over here many I talked to refused to do more than 8 hours a day. I didn't understand until... -- ever tried to do a hard physical work several days in a row? How about the entire life?

> don't have to deal with ageism

But have to deal with knee joints and back pains. Don't underestimate the joy of physical work at an advanced age.

> their skills stay relevant regardless of fashion trends

Old ones refuse to service modern equipment, say "I am a plumber, not an electrician". Admittedly, probably because they have got enough pure-plumbing work to do as it is.

Don't know about the US, but in much of Europe plumbing has definitely been 'offshored' in the sense that much of the work is done by non-locals brought in short term.