“We devote all these resources to creating, basically, country clubs with libraries,” Barry Schwartz, a longtime professor of psychology at Swarthmore, told me. Swarthmore, he said, has resisted the trend more than other colleges — no water park there — but has not been immune to it. No institution is, and Mr. Schwartz placed much of the blame on sharp increases in tuition and other expenses. When families are asked to pay $60,000 or more a year, the transaction takes on a more bluntly commercial aspect.

“Costs go up,” Mr. Schwartz said. “Parents expect to get value for money. They measure value in a different way. We provide that value, which raises costs, which creates more demand, and the cycle continues.”

But amenities aren’t all that is different. The interactions and balance of power between student and teacher are as well. I don’t recall ever filling out a professor evaluation when I attended the University of North Carolina at Chapel Hill in the mid-1980s. It’s possible that such forms existed, but they were not used consistently or presented to us with any sense of urgency.

The opposite was true when I taught at Princeton in the spring of 2014. Students could not see their grades for a given class until they had filled out an extensive report card, including numerical ratings, on the class and on the instructor or had formally declined to do so, which few did. The instructor was privy to those ratings, with the students’ names erased.

I’m told by many of the professors I know that this practice is more or less the norm. Coupled with websites on which students rate their teachers, it has enormous bearing on how fully enrolled an instructor’s classes are, on his or her reputation and — thus — on his or her career. And what is perhaps the greatest driver of student satisfaction with a professor? The greatest guarantor of glowing reviews? The marks that the professor doles out. Small wonder that grade inflation is so pronounced and rampant, with A’s easy to come by and anything below a B-minus rare.

Students get the message that they call the shots. Catharine Bond Hill, the president of Vassar, told me that when she began teaching in the 1980s, students never came in to complain about grades. “And back then,” she added, “you could get a C.”