STEM is such a broad category that anyone promoting STEM fields as a solution to the college debt problem is obviously just repeating what they heard from other people. There are a ton of underpaid and overworked people in STEM.
The third category isn't as fortunate in the job market, like say a biology major. How about Dev OE, OS. Doeos? Wow, that almost works. But it kind of reminds me of nxivm though :-)
E.g., CS PhD have plentiful $200K+ job opportunities after graduation and a relatively labor-friendly faculty market. Meanwhile, many mathematics PhDs postdoc into their 40s.