An elite school having a similar rate as the bad parts of Mexico would still be shocking. But, Mexico is counting deaths not killers so victim rate is a better point of comparison.
Some US cities have similar rates. Even then, it's not the same as comparing to other schools. And yeah, murder rate vs murderer prevalence would would different things. I don't think there's a lot of data on the latter.
Plenty of locations have rates around that. That's why it's important to compare similar sized areas.