I remember thinking these same tings when I was growing up too, and getting that sort of "duh" reaction from my older brother (probably PG) when I needed more explanation for things than he did.
We have had many discussions with DD8 about the rate at which she learns and how many times there will be others who need more explanation than her before they get a topic. It hasn't always translated into understanding however. She still has days when she gets very frustrated about trying to find some deeper meaning in a really simple question or instruction.
We have had to work on how she reacts to others who ask for more explanation too. (Think exasperation at the "stupidity" of the questions

)