I’m single, and I could never live on that. Wish I could (then again, I live in the D.C. area, and it’s almost impossible to live here on ANY salary!).
Your situation is a matter of residence. I can see that it could be done depending on where they live, how much they pay for housing, etc. Place of residence has a huge bearing on this. My wife and I easily lived on less percentage-wise in the mid 70s when I went back to school. We weren’t starving but it was tight for most of that time.