Eugene Volokh, in a post defending Strom Thurmond against the charge of child molestation, notes a handy table that lists the age of consent in all fifty states, and comments:

I also suspect that the table is mostly designed for people who like to have sex with teenagers, but it seems to be pretty accurate, and I’ve found it useful even for more academic purposes.

Now, I’m not an expert on such matters, but it seems to me that having sex with teenagers is quite a popular activity, particularly among college students; the only thing I can figure is that law professors—the only academics who, as a group, don’t have much contact with the 17-21 demographic—are unaware just how much sex goes on among undergraduates.