Good questions. Dunning Kruger says the more intelligent one is, the more one thinks everybody else is too, and the less intelligent one is, the more one thinks everybody else is stupid.

I also recall my frustration living in America and so many assuming one doesn't know something. A friend who had lived there for 30 years said that in other countries, one assumes that others know the same thing but in America, there is the assumption that others know less.