The concept of many students going to uni, or worse even to school, by car baffles me; usually they have good public transport connections and enough bicycle stalls, but I guess this is the US?
In any case, many US universities are in rural towns that only really exist to serve that university. And you would find that the transportation patterns are entirely different for a big city school vs a rural one. While the bicycle transportation options in a university town are generally pretty good, it's also true that many people prefer to drive vs biking in 40F rain, -10F ice, or 90F and humid.
But also, outside a few areas in the US on the coasts, this country is much bigger and more spread out than EU countries. This makes driving a necessity for many people. People mostly burn gas because the alternatives aren't practical.