what to wear to a nonprofit interview

My new pet peeve is becoming people who think that because they're interviewing at a nonprofit, they can dress down for the interview. I've seen too many candidates lately in business casual, which I'm pretty sure they'd never wear for an interview at, say, a bank.

Why are people doing this? Do they think other nonprofit standards are going to be lower too, like performance accountability? They're not. (Or at least they shouldn't be; if anything, they should be higher, given the importance of the work of many nonprofits.)

This is my PSA for the day: If you are interviewing at a nonprofit, you still need to wear a suit.