Colleges, STEM, humanities...

For the purpose of this discussion, this means?

From a state university point of view, the state subsidy that allows for lower in-state tuition is not unlimited, so the limitations on semesters and credits exist to avoid having any one in-state student consume more than his/her “fair share” of the state subsidy, and allow more students the opportunity to be educated at the state university.

My flagship U now charges extra for more than 18 credits per semester. There is more room in upper level classes so freshman admissions are limited and students can transfer in, presumably to take classes for their major and not those introductory classes mainly taken by freshmen. My thought was to emphasize that one pays for the knowledge acquired via courses, not to get a piece of paper.