Well....the Frogoten Realms has roughly 100 arcane spellcasters alive at any one time that can cast wish, plus at least 100 divine ones that can cast miracle.
Mystara...the Empire of Alphatia has 1,000 wizards of 36th level (say 20th)
The Volo guides for FR, as well as many other things written by Ed Greenwood show a good 'high magic' world for common folks: plenty of shops or taverns have a guardian golem, powerful spell wards, magic items and a high level spellcaster or six. Aurora's shops alone operate a world wide teleport/portal system. And that is just the stuff covered by the rules, as FR has tons of 'unknown mysterious magic'.