Personally I play DnD in a Forgotten Realms inspired (Mostly Forgotten Realms but like a number of years in the future with a new Mystra)
I'm the DM and one of the things I brought up was basically "Yeah there's magic, but it sure as hell ain't evenly distributed"
Wizards are a secretive bunch, and the higher level the spell the rarer it is to find let alone someone who can cast it