I never pay attention to people's "maturity levels", because it usually isn't quite right.

(however, it is pretty easy to see that I'm the most disciplined student in my school... I live in a world of Rednecks...)

There's a bit of a phenomenon with skills, being that the more you become skilled at something, the more you feel like you still have to learn. People who are noobs at something don't know enough about it to know how unskilled they are, but as you become more skilled you ironically become more aware of how much you still have to learn. To me, it seems like ranking your own maturity is the same way. Immature people aren't mature enough to understand how mature/immature they are, so they usually put a high number. More mature people are able to recognize their faults and therefore might put a more honest (and lower) number.

I believe that maturity is an illusion that people believe comes with age to fool themselves into doing certain things.

I completely agree. It's also the same with age (although more quantative). I disregard it completely because I know adults that act less mature than a 13 year old. I think both of these questions should be thrown out of application process as you can't really know what the person is like until you talk to them