This is not quite true.As an example of Ed Greenwood's setting power levels, Daggerford is a small (400 people) town in the middle of nowhere.
Daggerford also includes a host of hamlets with hundreds more farmers (mentioned in passing and otherwise ignored), and overall states it's about 1000 people who live in the area. It's also not the middle of nowhere. It's the seat of a ducal castle (many of those high level people are his family and retinue): he might be an unimpressive duke, but he's not minor nobility either. It's a prominent stopover on a major trade route thus lots of (potentially wealthy) caravans pass the area, and regarded as a significant strategic point by the local realm, Waterdeep, for that reason. There's also a little snippet about the availability of stuff in Daggerford, which is low for high end stuff including basic potions (double normal cost), and in terms of magical items somewhere between nil and more-by-accident-than-design as the shopkeepers probably wouldn't realise even if something they had was magical.
So do you see my point?
I accept that as a player experiences whilst playing, FR seems full of magic. But even the campaign setting you've chosen illustrates that for the majority of the population, it is not - just they are all but ignored and removed from players' notice.
I also accept there can be a disparity (apparent or real) between the game and the worldbuilding. This may be sheer inconsistency. It may be, or be akin to, what people in computer gaming have termed "ludonarrative dissonance". A setting needs to meet the requirements of the gameplay. If a mage requires training, there has to be a more powerful mage available to do so. A powerful priest should probably be on hand with raise dead just in case one of the PCs gets themselves killed. At very high levels, there needs to be the odd place in the world where level 20 demigods can go and have a challenge. So therefore, the game must provide even if "unrealistic".
However, I see no reason the settings must prove the overall worldbuilding "wrong" or vice versa, when there's no need for them to be inconsistent. The explanation is that campaign settings represent "points of interest" where stuff is going on and more people of power are for adventurers to be and gaming to occur, whilst the majority of the (populated) world that's not in a campaign is much lower power and more boring. The PCs thus operate in a privileged environment within the wider world.