The standard "wisdom" is that Americans have not gotten wealthier in the past twenty-five years. Lots of people believe this, even extremely intelligent people like Richard Stallman. And yet, I must believe the converse when I look at the parking situation at the local colleges. Clarkson University built a new parking lot in front of Cubley-Reynolds(1) and expanded the Hamlin-Powers(6) parking lot. SUNY Potsdam built a whole new lot out behind Bowman South(not even on the map yet).
The demographics are such that student population is down from when I attended Clarkson. At the time, we had involuntary triples, and single occupancy dorm rooms were only available to seniors in the New Dorms (which, by the way, they still call the New Dorms). Potsdam State still requires freshmen and sophomores to live on campus in order to keep the dorms at full occupancy. They didn't when I was in college. So, there are no more students, and substantially more cars. The kind of students who attend Clarkson and SUNY Potsdam have not changed as far as I can tell.
The only explanation is that Americans have indeed gotten wealthier, and that is reflected in more students who can afford cars. Cars have not exactly gotten cheaper either. They have more safety equipment, and more luxury equipment. When I was a child, only a Cadillac had window washers and electric windows. Now all cars have them, or very nearly.