The scenario posited in the op was villages being burned and people murdered, which is very much an outside intervention or die situation. It is also exactly the sort of situation where the local authorities should be able to deal with it before any itinerant mercenaries can even hear about it.
The land based version of a privateer is a mercenary, not an adventurer, and adventurers as used in rpgs have basically nothing in common with privateers anyway. Nor do they usually have much in common with realistic bounty hunters, explorers or indeed any of the mentioned professions. As a group they tend to have such diverse skills that calling them by a collective noun doesn't even make sense.
I have a hard time imagining an inquisition hiring a sheriff, who already has a job with a wage, to help them. Or to be more precise, I can't imagine a sheriff (the medieval kind) keeping their position after doing so. Skipping work to do something else is fine when you're self employed or don't technically have a job, but when you're a bailiff or a knight or similar failing to perform your duties without a damn good reason is a big deal.
And while I'm not an expert on the issues Britain suffered in India, I'm pretty sure the snakes weren't actually a problem before the bounty, or at least not one that needed a bounty to try and solve it. Barring unusual circumstances like the Beast of Gevedaun or Paris in 1420, people who live in an area are usually able to deal with the animals that they live near, or they haven't have been living there for long.
As for settlements not dying immediately, I don't consider a settlement lasting ten years before dying instead of three a win, in the circumstances in which I'd find such a village I'd probably tell them to go back to a proper town and move on rather than enable their self destructive desire to strike out. In most contexts I might actually consider the settlement dying to be the win. There's very few situations I can think of where a bunch of people travelling beyond the nominal borders of their realm and building new settlements in lands already occupied is a good thing. In the OPs context of goblins, the idea is clearly that the goblins are attacking lands that have established human settlements, and which should be protected by the same infrastructure used to resist invasions or deal with rebellions or brigands, in a 'fringes of civilisation' context it basically means the villagers are encroaching on the goblins rather than the other way around, and in such a context the village is the bad guys.