I think about my lab classes and typically these were separate credit hours. More money to the university. Outside chemistry, we were using outdated equipment that wasn't getting refreshed/bought new.
If what you are saying is true, Humanities needs to cut costs of their credit hours or double down. For entertainment degrees (art, music), its prohibitively expensive to casually obtain the education. For business/politics/psychology, there is at least some sort of return on investment to be expected.
For your second point, I've never heard of a university that charges different credit rates for different majors (outside of special stuff like paying for certain PE classes), but that seems like it would be a university policy, not a department policy.
Is the university responsible? The arguments seem to be based on majors that have a poor job market.
For existing agreements, of course.
Going forward, for those who are the real beneficiaries of the loans, they should have a skin in the game.
Why aren't universities standing behind their product and offering financing without the unusual non-dischargeable nature of the loans? Do they not stand behind their products?