It was shocking to watch how sheetrock work became so shoddy as the Mexicans took it over, and that applied and still applies to all the trades.
People overlook that immigrants from Europe were skilled craftsmen and/or used to being customers of skilled craftsmen, the best in the world, look at the cities and nations they came from and then compare that to Mexico, Mexicans and Latin Americans have never been known for being skilled at any of the things they do here, they came from places that were built as dumps with no standards or expertise with construction materials.
Mexican villagers that know nothing about landscaping replaced Japanese and white gardeners in California for example, and it shows.
Modern American immigrants come from cultures without knowledge or standards, yet took over those roles in one of the world’s richest most advances societies, from dirt floors and tin sheets roofing to advanced Western building and housing.
You are correct. Many Europan immigrants really brought professional skills with themselves to America - to America‘s benefit.
But also to their own, as they could achieve a standard of living in America which they never would’ve been able to reach at home…