The majority of rules (including spells) revolve around combat. There aren't many spells for things like "ensure survival during childbirth".
In every edition from 3rd, magic items are really expensive. You either need to be an adventurer, noble or plain rich to buy them. Barring some cheaper consumables, I think only the rich are going to have items. A peasant family might have one healing potion for emergencies, enough to survive an accident but probably not even enough to survive a raid.
Adventurers, naturally, tend to get items that boost their combat and harsh environmental survival ability. Nobles might tend toward items that protect their families or are useful in politics, disease-treating items might fit the first category, and items that make scrying on them harder the latter.
In 4e, many spells that used to be "free" weren't. The Remove Affliction ritual would come up a lot, and it's expensive. Contrast with 3e and 5e, where such spells only cost slots. For adventurers, this is a big deal. For the village priest, there's much less competition. Of course, clerics have a limited number of slots. They can probably keep the disease level down, but can't handle a massive epidemic.
Some classes don't really "belong" in a small town. A ranger makes sense. Hunting, tracking, and general woodcraft are important in the wilderness. A ranger might be hired to hunt poachers, or a ranger might be a poacher. By contrast, paladins probably spend their time at large churches or military encampments. A wizard who isn't adventuring is probably studying at a tower, university, or lab, and only the first might be found anywhere near a small town.
Non-adventuring rogues don't advertise that they're rogues. They don't always wear leather armor, festoon themselves with daggers, skulk around where anyone can see them, etc. In today's world, a mugger probably looks just like the guy you sat beside on the bus, or the woman you drove behind in your car. Of course, this means rogues need "day jobs" for cover.
Rogues have a variety of skillsets too. A rogue might work as a "scout" for the military. People who know their skillset (and are loyal to the same country) might disagree that they're a rogue. Such a rogue doesn't need a day job "for cover" as being a rogue is their job.