I don’t know that this is a reasonable generalization. Certainly in my CS department one could write a thesis to receive an MS, and no MAs were offered. Just one data point, from a very large state school; YMMV.

You're correct, it's not a reasonable generalization. See my reply above.

The essence of my answer is based on the way things were in my graduate programs at my university when I was in school there; and some observations from so-called terminal Master's degree programs.

In what way is it “greed” and not “how much houses cost”?

Inasmuch as incumbent homeowners pressure politicians to rig the market in their favor.