If they're undergrads that's probably counting their parents' income, not their own.

I worked in University IT and made over $30K working part time during the school year and full time in the summer, as did most of my coworkers. Also, we made slightly more than the normal person because Social Security tax is waived for working students, so that's like a 7% bonus.

When you're in the Bay Area and your students can choose to work for the University or go get a paid internship down the road, you have to compete on wages.