I went on an interview like that in 09 for a job in the public schools, working with kids after class ended for the day. They had so many candidates they did group interviews the way you describe.

I thought it was kind of degrading, especially since I was nowhere in the running. The other people who were in my group were ridiculously overqualified, so I made no impression, really. (The job paid $8.25 per hour, part-time, no benefits). I live in West Michigan though, so pretty much every interview is weird and depressing, just in different ways.

Good luck! You never know, you might enjoy it. (Probably not though.)