Everyone has been part of someone's evidence that everyone else is stupid. Smart people do stupid things too.
George Carlin was funny, but there is no scale, or measure for average stupid. Stupid comes from lots of places, haste, pride, dumb, inexperience, alcohol. It seems to afflict most people fairly equally. I feel like anyone who tells me everyone is stupid, is projecting.
What exactly would you like me to look at "that public education teaches?" That is a little too broad of an area for me to understand what you are getting at. Or are you using that in the common way, to blame the schools for not raisin up them children right?