think the main problem is that people are going into jobs that there isn't any actual demand for.
Partially because demand for human labor relative to overall market size is decreasing. Some call this "increasing productivity".
For example, I've actually met somebody who majored in History and then complains that he can't make a living wage. And I've seen many more art majors who think that the world is going to hell because not enough people care for the moronic crap art that most local art districts produce.
I both agree and disagree. I studied math, EE, CoE, and CS. Not because I'm pragmatic, but because I've been a science/technology nerd since I was little. My fiancee did philosophy for her undergrad, something even less pragmatic for her masters. Today, she makes as much as me (working in a field totally unrelated to any of her education), despite being 5 years my junior.
The same is true for some majors that actually paid a lot in the past, and otherwise may still pay a high hourly rate, but there are so fucking many people in that career that your odds of finding steady work are crap. Case in point, lawyers.
Excellent example. Can't really argue against this.
Meanwhile there are lots of jobs that pay no less than $20/hr that can't be automated and have plenty of positions that need filling: HVAC, plumbing, auto and aviation mechanics (good mechanics can easily pull a 6 figure sum, by the way) construction workers, electricians, landscapers, maintenance contractors, and many more.
Going from lawyers to mechanics isn't exactly a huge leap forward. That's the point, that there is no labor shortage, not in the labor market overall. There is a shortage of demand. Some fields are doing okay, like the blue collar trades that you mentioned, largely due to the fact that they're both harder to automate and relatively immune to globalization-related concerns, which helps keep demand high. Other fields, not so much, because if there was, you'd easily be able to point to evidence and say "See, they really can't find people to do $job! They're offering ludicrously high salaries and still these positions go unfilled!", much like you just pointed to those trades, which account for only a tiny share of the labor market, and as such are more the exception than the norm.