Why do people have University license plate frames on their cars?

They are probably proud of where they went to college, teach at, or maybe their kids go there.

Some people love to decorate their car with their personality, and the license plate frame is one of the easiest ways to do so. As to why people use university license plates, it could be because they went there and enjoyed it, or they have a son/daughter who goes, or maybe they’re a teacher there, or maybe they just like that school’s sports team. My university offered these window stickers and I had bought one and was going to put it on, but then I found out what my university really was like (hint, politically corrupt), so I chose not to put it on. As for me, I’m not actually sure what mine is.

A lot of people like to show support for schools because they are fans of their football, basketball, and other sports programs. Its the same thing as someone wearing a baseball cap with a sports team on it.

All people align themselves with particular social groups as a way of forming and validating their own sense of identity. Your class probably should have covered that. This applies to every aspect of life, books clubs, McCain/Obama magnets on cars, t shirts. Anything that identifies with a particular brand or idea generally has the same appeal.