Sword of Spirit
Legend
That's the point, the ones who don't cast spells aren't in the adventures. The game fiction assumes the world is full of people who aren't plagued by monsters or hatching evil plots for world domination. The farmers farm, the laborers labour, and if they get hurt the local priest can't cast Cure Wounds on them. They are just part of the background scenery, like trees, birds and squirrels.
It's pretty much essential to the standard D&D plot set up that villages have few, if any, people with class levels. If they did, they could deal with the monster infestation themselves, and wouldn't need to pool their life savings to hire the first group of adventurers who happen along.
Well, I didn't really want to spend the time, but I went ahead and did it anyway. Cold hard, published facts to back up what I'm saying.
2e AD&D detailed basically the entire town of Daggerfall in a dedicated booklet of about 35+ pages. Here's one of the intro paragraphs for context:
"This self-styled city is a town of about 500 folk. The town is the largest stop on the
High Road between Waterdeep and Baldur’s Gate. It’s home to human craftsmen, a few
halflings, and a handful of folk of other races. There are about 20 farming hamlets within
a day’s walk of Daggerford (15-20 miles), each of which is home to around five families.
Each hamlet has a fortified building where the residents retreat in case of raids. There are
also isolated farms and a few estates of minor nobility. In all, about 1,200 people depend
on the Daggerford market for goods they can’t make themselves." - The North - a Guide to the Savage Frontier, 1996.
There is a temple of Lathandar staffed by Liam Sunmist, a 10th level cleric.
There is a shrine of Tempus staffed by Baergon Bluesword, a 7th level cleric.
There is a shrine of Tymora staffed by Bando the Lame, a 7th level specialty priest.
There is a mosque to Tyr 2 days to the east staffed by Elorshin, a 6th level specialty priest.
It doesn't really tell us if any of the other clergy that might be at those temples or shrines are spellcasters. But let's read the shrine to Chauntea for context:
"95. Chauntea’s Shrine (Harvest House)
Maerovyna (LG hf D9) presides over this large, stone establishment
which is also known as Harvest House. Not
far from the Farmers’ Gate, she administers 14 priests and
about 30 lay brothers between 2nd and 5th level. This
shrine to the Great Mother is of great importance to all
the farmers and ranchers of the Daggerford area, as the
priests spend their time fulfilling the needs of the community,
including blessing fields and researching new plants.
The oldest apothecary in town is Duneden (LN hm C3).
He has the ingredients for most common spells, but he depends
on caravans for more exotic ingredients."
There is also the Physician's Order:
"This guild hall is home to apothecaries, physicians, embalmers,
and healing clerics"
Moving on to other published settlements...the next one I took a gander at is in Night of the Walking Dead, a Ravenloft adventure, so we're looking at low magic.
In the 300 person village of Marais d'Tarascon, there is only one church, and it is presided over by Brucian, a 2nd level priest.
I don't have a lot of 5e adventures. I'm less than half way through reading Out of the Abyss, but here's what I've seen so far. The Svirfneblin in the small village of Blingdenstone have only one religious organization, and it's overseen by at least one priest (the NPC statblock that is a simplified 5th level cleric). The 500 Kuo-toa have an archpriest in their little neck of monsterdom.
I've got pdfs of a bunch of short freebie 3e adventures that WotC put out--so not anything recognizable. Let's see what the clergy are like in the first 3 villages I can find that have clergy.
Eye of the Sun: 3rd level Adept
Ghosts of Aniel: Two 1st level clerics, and a note that many of the highest level characters in the village had recently died. They seem to have followed the DMG instructions for giving classes to inhabitants of towns. The DMG from 3.5e (p.139) says that a typical hamlet of 200 people (Aniel has 146 currently) would have one 3rd level cleric and two 1st level clerics, and they seem to be actually following the suggestions in the DMG (though it would have been the 3.0e for this adventure).
Last Breaths of Ashenport: 6th level Adept
I've only addressed small villages because they are telling us about all the shrines and temples in them. Some of these have maps with every building on them! They aren't just telling us the ones that have casters and assuming there are others that don't. No, this is what they have--and it's spellcasters.
Are there any counter-examples you can find from official published settings or adventures?