I don't really have an opinion on the topic but I think the general argument is that the appropriate comparison would be domestic, not abroad. Meaning, the system is used to depress wages compared to the wages of a domestic worker. Wages matter in a relative sense, or employers in Manhattan could pay the same as those in Oklahoma. In the absolute sense, many, many American wages (skilled and unskilled) would be considered high.

I think part of the argument (and where your home building analogy may not be quite appropriate past the superficial level) is that much of the work is done using U.S. tax dollars, meaning Americans are funding a system that simultaneously depresses their own wages.

>Go and look at the local auto mechanics, electricians, carpenters in your area and count how many have been born overseas. Because where would you learn those skills as an American?

I've been lucky enough to be able to live multiple culturally distinct areas in the U.S. and found this to be very different depending on location. In some areas, like the Rust Belt, that have a history of blue-collar work, I don't know that I saw many non-native workers in the skilled trades (albeit there was probably still a higher percentage in the unskilled labor market). These areas also have a larger union presence and with that comes apprenticeship programs where they aren't forced to learn those skills at their own expense; in fact, they're paid to do so. Other areas that have a larger immigrant population, I'd concede your point that most of the skilled trades were immigrants but they didn't seem to have the same systems in place. It's possible your conclusions might be an artifact of sampling bias. But I would also agree that, culturally, blue-collar career tracks may be disparaged in the U.S. to the point where fewer Americans are willing to pursue them.