You were slightly shocked because you are misunderstanding the table. Those are FTE (full-time equivalent salaries). The actual students work at most 50% time (during the 9 month academic year), so get at most half the amounts listed there.

I remember being a Graduate student in math at UC Berkeley in the late 90s, and getting just over $13K/year - it sucked (and grad students were striking back then)! So I also took out many student loans, which worked out for me because my salary once I got a real job was enough to pay them back very quickly (as I was used to living on so little money). I was a grad student at NAU in Flagstaff before that and got under $9K/academic year...