In this June 17, 2013, file photo, University of Oregon graduates make their way through campus during the traditional Duck Walk preceding graduation ceremonies in Eugene, Ore. (Brian Davies/The Register Guard via AP, file)

Whether it’s high-school seniors graduating with top scores on Advanced Placement tests or college students taking a class or two during the summer break, their goals are usually the same: to save a few dollars on the tuition bill by finishing their degrees early.

But as many of them come to discover, college tuition pricing is just as maddening as the family cable bill (just a lot more expensive). Much like cable providers spread out their huge programming costs by forcing customers to buy network bundles even if they don’t watch the channels, the college tuition bill is bundled as well.

On most four-year college campuses, full-time students don’t pay by the credit hour (think by channel on your cable bill). Rather they pay a flat fee for the semester (a programming package on your cable bill) and are typically allowed to take as many courses up to a certain limit.

Such a pricing structure works largely in the favor of the college or university in two somewhat contradictory ways.

For one, about half of the full-time students on campuses these days take fewer than 15 credits a semester, which is equal to about five courses and the amount usually needed to stay on pace to graduate in four years. That’s why only about 40 percent of full-time students graduate in four years. In essence, colleges are collecting extra tuition dollars from students who don’t take a full load of courses, and then collect again when the students stay on campus longer to graduate.

Second, many students collect too many credits for their degree. On average, students now accumulate — and pay for — 136.5 credits for a bachelor’s degree when only 120 are needed, according to Complete College America. Some of those extra courses are because students switched majors or added a second major. But in most cases it’s because the credits students had earned elsewhere — whether through A.P. or college-level classes — weren’t accepted by the campus granting the degree.

The credit transfer business is arbitrary at best. Credits earned at a community college might be accepted at a public university across the state, but not one in the same town. Colleges say they reject credits they don’t deem worthy, but what they are really doing is trying to protect their bottom lines, just like the cable companies. Each credit a college accepts from somewhere else is revenue they forgo.

Those dollars add up quickly, especially at large universities. The College of Arts and Sciences at Ohio State University is facing a $4.6 million deficit next year in part because students are bringing in credits from elsewhere, including AP courses.

About 20 percent of high school students in the U.S. earn high enough AP scores for college credit, up from 12 percent a decade ago. That allows students at many colleges to finish their course work early. At Georgetown University, for example, about a third of seniors go part-time in their last semester because they already have completed their degree requirements, Randy Bass, vice provost for education, told me.

But even as students find new and cheaper pathways to earn credits before they step foot on campus, colleges usually act in their own self interest to find ways to protect their revenue. As long as tuition pricing structures continue to operate the way they do right now, there is little incentive for colleges to become more inventive about how they deliver education.

A few weeks ago, Verizon announced new slimmed-down packages of cable channels, without ESPN (which promptly sued Verizon). The cable companies are worried about losing customers to online streaming services. Colleges and universities don’t have to worry about a mass exodus of customers yet — though college enrollments are down. But as colleges increasingly compete for students, a key differentiator for students in the future will be between those colleges that accept their credits and those that don’t.