In the spirit of this question about photos on CVs, I'm wondering why applications to grad programs seem to universally ask for the applicant's date of birth, usually right next to the applicant's name.
This is in sharp contrast to the standard practice in "industry" (at least in the US), where no age-identifying information is requested until after you've been hired, and even then the information is restricted to HR.
A few discriminatory practices such as requiring date of birth on the CV or dissertation seem to be finally going the way of the dinosaur, but this obvious point of potential discrimination persists. Why?