Yes. And you’re right that such murders are rare, but murder is rare in general. But historically speaking, murder is rarer now than in past ages.
The how and why will always be very situationally dependent, though.
In a community such as you describe, the killing could occur because a wandering miscreant- a true murderhobo- saw the gold and took it by force, little realizing such wealth was all around him as he makes his getaway.
Or perhaps someone in the community incurred a debt the last time he went to sell his wares at the county market, and no one knows about it. But it is nearly due, and he hasn’t done so well lately. Desperation sets in...
A farmer’s well runs dry and he needs money to dig a new one- more than he expected, too, since his own tools have fallen into disrepair with lack of use, or the new spot to dig is in difficult, rocky terrain.
I agree regarding the wandering murderhobo, but the rest seems a stretch to me.
People in such small communities are inclined to help each other out. It isn't pure benevolence either, but rather enlightened self interest. In an isolated town of 70, everyone serves an important role to everyone else's well being. If the thieves guild chops off Bob Blacksmith's hand for failing to pay his debts, that injury will not only cripple Bob but the entire community. It's not like they can hop on Craigslist and hire a new blacksmith. If they're lucky, Bob's less experienced apprentice knows enough to take over the business. If not, they're left bereft of a blacksmith for an indefinite period of time.
I see it being far more likely that Bob would go to the community, and after much grousing they'd find a way to help him. Granted, he wouldn't truly be off the hook in all likelihood. He'd most likely be basically an indentured servant for the town until he worked off his debt to them.
That could be an interesting adventure though. The townsfolk have gathered the coin to pay the debt, but they're worried about transporting it to the city. They ask the player characters to deliver the payment in their stead.
This creates an interesting opportunity for foreseeable consequences. Many players will choose to fight the guild rather than letting them exploit honest townsfolk. But that could well have negative consequences for the town, if the PCs fail to finish the guild off. ( This is also an opportunity to telegraph that threat by literally having the thieves make threats.)
Personally I dislike fairy tale worlds where every good deed has good consequences and everyone lives happy ever after once the PCs passed through the area. Thats both boring and unrealistic.
Sure, but the converse is also boring and unrealistic.
To have an interesting and realistic world, you need to mix together the good, the bad, and the neutral.