Yes people are really that ignorant. I honestly think that a lot of the time when people do it, they don't understand that Greek letters have English equivalents.
Then again, before the symbol font was in widespread use, sometimes people (nonmembers and members) would use English Es instead of Sigmas when writing, trying to make the name of the group "look" the same, I guess. This resulted in some people calling my sorority Alpha Epsilon Alpha.
