We've made these jobs seem "dirty" and low class when they're not.
If you're a welder you'll get a very good starting wage, and while it will never hit stratospheric levels, the upper end when you you've had years of experience and have worked to increase your qualifications can be extraordinarily generous.
I know two highly qualified welders that work on oil plant equipment and they make so much money they can afford to take half the year off to do whatever they want. You don't want random idiots welding pipes in a billion dollar plant, and you need to pay for that kind of talent.
Consider: Tech workers often get paid very well, but I don't know of many that get overtime.
For example the requirements to go on my technician course in the UK back in the day required 6 O levels (exams taken at 16) for the Bank only 4. Ok it was a specialized for the local industry themo fluids one.
When enough people realize just how much of it is smoke and mirrors, I think the common snobbery towards those "dirty" jobs would dissipate. Right now, it's self-reinforcing, because being "better than those guys" is part of white collar identity, regardless of pay. It reminds me of the racial arrangement in Jim Crow South, where even the most poor whites would find solace in that they're not on the lowest rung of the social ladder.
Also this would require employers to commit to training in away they will not want to do and because of the one size fits all they would have to pay for a generic learn the needed skills and knowledge.