Recently, Mitzenmacher had a nice post about conference budgeting. One interesting tidbit: this year's registration fee for STOC will be around US$500, and he asks, "At what point do registration fees become a noticeable concern?" Many commenters agreed that $500 was outrageous; meanwhile, in the IT community, last year's ISIT registration would have set you back a cool US$850.
However, concerning student registration rates, Mitzenmacher also asks the following question: "... every student who attends is actually a loss, that has to be covered from elsewhere. Is this the right way to go?"
At first, it seems like the answer should be: yes, of course; helping students is good. But thinking back to my graduate student days, I never paid for conference registration out of my own pocket -- it was always covered by my supervisor. Thus, the primary beneficiary of a student rate is a professor with many graduate students attending the conference -- who, as a result of his/her large group, is already well funded!
In fact, if student rates are offered at a loss, that loss is made up by professors (like me) with limited funding, who can only afford to send themselves and maybe their one student. So are student rates actually regressive?