Free, or reduced, tuition for the children of college professors is a perk commonly offered in private universities.
I don’t know how it is today, but for a very long time there was reciprocity among the ‘elite’ schools for professors’ children to get the same deal if they chose another school in that circle. I.e. a Harvard prof’s kid could get free tuition (or enormously reduced) at Williams, or Penn, and vice versa.
I have friends whose spouses work for local universities. Two are at private universities, one at a VA state school. Guess which doesn’t offer the kids half off the tuition?