I am often curious about the actual salary numbers for the trades versus STEM and often see comments around trade positions being high demand and "none . . pay poorly."

I googled around a bit to grab some numbers. I think the below supports the idea that the trades mentioned by GP have median earning numbers very close to the median earning numbers for a full time worker in the United States, maybe a touch less if we grouped all the trades together.

The demand question is less clear to me. The BLS source implies less demand (measured by job growth) in general for the trades than the "average" demand growth for jobs in the US.

The U.S. Census Bureau lists the annual real median earnings at $41,535 in 2020 for all workers with earnings[4] and lists the annual median earnings at $56,287 in 2020 for people who worked full-time, year round. [1]

Plumber - median $56,330, demand growth, slower than average [2]
HVAC tech - median $50,590, demand growth, slower than average [3]
Electrician - median $56,900, demand growth average (actually 9%) [4]
Framer(Carpenter) - median $49,520, demand growth, slower than average [5]
Bricklayer(Mason) - median $47,710, declining demand. [6]
Software engineer - median $110,140, demand growth, higher than average [7]

The same source of data projects the average job growth to be 8%, so "slower than average" and "higher than average" are in relation to that number.

It gets interesting trying to generally compare demand for STEM to the trades. The BLS estimates about 84,700 openings for electricians per year for the next decade. Contrast that to, for example, chemists - the BLS estimate there is 9,100 positions per year. I didn't find a really great source for the number of BS degrees awarded per year to Chemistry majors, but numbers seemed to be between 14,000 and 17,000 per year.

When I think about supply and demand in careers, it seems to me that STEM is weird. People say "STEM is harder and just worth more in the end" but there seems to me, based on the numbers, for there to be a large "winners take all" effect. But it's hard to measure how many BS in Chemistry holders go to medical school, law school, or take project managment jobs versus being baristas in your local coffee shop. I did find one source that implied the highest percentage of graduates with "Physical Science" degrees (which includes chemistry graduates) at 8.5% work in post-secondary education.

One thing I know for sure - my organization (academic medical research) often hires post-docs that start at a little less than the US median earnings for full-time workers. And there seems to be a lot of competition for those post-doc roles. Salaries do go up over time.

[1] https://en.wikipedia.org/wiki/Personal_income_in_the_United_States
[2] https://www.bls.gov/ooh/construction-and-extraction/plumbers-pipefitters-and-steamfitters.htm
[3] https://www.bls.gov/ooh/installation-maintenance-and-repair/heating-air-conditioning-and-refrigeration-mechanics-and-installers.htm
[4] https://www.bls.gov/ooh/construction-and-extraction/electricians.htm
[5] https://www.bls.gov/ooh/construction-and-extraction/carpenters.htm
[6] https://www.bls.gov/ooh/construction-and-extraction/brickmasons-blockmasons-and-stonemasons.htm
[7] https://www.bls.gov/ooh/computer-and-information-technology/software-developers.htm