The cool thing is that while "america" has raised their kids to shun "blue collar work", that has created a shortage of people willing to do that work, and made for some really good wages.
I read a lotta, lotta stuff about the Klondike Gold Rush during the year before a friend and I took my Land Rover to the Yukon for a five week camping/fishing trip.
And something I learned from all that research is this: Given the number of people who went to the Yukon in search of their fortune, very, very few of them actually made one. Most of the people who trudged up there and dug for gold came home poorer than they'd been when they went up.
The people in the Yukon who totally cleaned up in terms of making a fortune were not the miners. They were the guys who sold eggs to the miners, who sold shovels to the miners, who sold glass to the miners for the windows in their cabins, and so on.
Kevin is correct, I believe. Society, at least western society, has come to look upon "the trades" as being low-status occupations in life. Which is ironic, because as Kevin points out, the plumbers and electricians and roofing company owners generally make more than the people who are looking down their noses at them. If money is how we're to judge status, then the trades folks have it all over the "edjicated" cubicle dwellers.
Referring to the OP's first post, labor at $120 an hour is not out of line these days, depending on one's location. Where we have our boat, labor is $100 an hour. I'm sure it's less in other places. The cost of labor is driven in part by the demand and in part by the cost of living in that area. I would expect in the southeast states, labor prices in general are lower than they are here or in California for example.
As others have pointed out, labor is usually charged by the hour although you sometimes find people like electricians who charge by the half hour. So even if it only takes eight seconds to change a radiator cap, you have to pay the fellow who's doing it for a full hour. The diesel shop we use charges from the moment the mechanic steps out the door to the moment he steps back inside unless he's going to continue to work int he shop on a component he's removed from an engine.
So in the case of our boat and where it is, the radiator cap may take eight seconds to change but the mechanic is going to charge for walking across the street, through the harbor's big parking lot, out the couple hundred yards of dock to our boat, getting onto the boat and down into the engine room, and then back the same way. By the time it's all said and done, he'll have been working the job for the better part of an hour. And diesel shops (or plumbers or.....) don't round down.