In the valley to do comercial plumbing you need to join the union and go through an apprentice program( 5 years and 1080 hours of classes) plus there is a lot of plumbing done for hospitals and clean rooms which takes more training and class work. After all of that is ready the trades have to work together and organize their schedule to get a given project done.

I don't know if the people making the programing is like plumbing comment realize how highly skilled a plumber is.