Grammar Nazi me

I just called a friend a moron for using the incorrect spelling of the word ‘aisle’. I’m still trying to work out why basic errors like that make me so annoyed, maybe it’s something to do with my pride in my own abilities, or my upbringing.
I accept trial and error as being a part of life but I can’t understand how we can all go through the same curriculum and come up worlds apart. I know, I’m being a pedant.