Plumbers have a lot of value and have to study for loads of certificates.
I’ve done PLENTY OF PLUMBING and have incredible respect for them. One of the most taxing things I did was trying to lay out drain pipe (below grade) while meeting the 0.25” per foot slope and making bends to line up with rough-ins. Looks EASY after it’s done, but I was TOTALLY DRAINED (no pun intended), mentally, after that...and that was an EASY JOB. Try doing the same when you’re dealing with 2x10 floor joists and can’t dip below the ceiling level below. The people that built my house had the pleasure of doing that...which is why I NEVER, EVER, call illegals dumb or unskilled. Until I can hold a candle to their work, I will always respect them...but they still need to leave.
So maybe you have a point. It’s likely a LOT EASIER and certainly MORE FUN for a 20-something to eat up mom’s and dad’s retirement to become a Shakespeare Sonnet ‘expert’ than to learn how to lay drain pipe or sweat copper.
But then that’s why I tell parents to tell their kids to SHOVE IT if they insist in getting a worthless degree.