It is admittedly true that, at least among humans, Alola is a peaceful land free from the sort of criminal gangs that plague lands from Kanto to Kalos. Yet Alolan restaurants are less happy about this than one might reasonably imagine, for they, too, pay a sort of protection tax (still collected in kind, long after the rest of the economy adopted money) to stay in business.
The custom of the Rattata or Raticate tax (for it is commonly called the former, but keen observers associate it with the latter) is perhaps as old as the first Alolan restaurant, or at least the first few owners to realize that, if they laid out an entree for the local Raticate and its Rattata pack, said pack would leave the restaurant alone. What the owners (who could seldom distinguish individual pokemon) did not realize was that the position of the "local Raticate" was a fiercely contested role, and that, eager to preserve a reliable food supply, Raticate would have their minions viciously fight one another for that privilege.
Alolan Raticate themselves seldom participate in battles, not because of their inherent weaknesses (most notably against the pokemon type whose name is synonymous with fighting) but because, like humans, they have other pokemon to do it for them. While they are powerful enough to defeat those Rattata or weaker Raticate who challenge their leadership, their large size and high metabolism leave them reluctant to expend the energy of a pokemon battle, and eager to discover techniques which require no energy at all. Although Alolan Raticate are often dismissed as lazy, stupid rodents, a pale imitation of their more fearsome relatives, they have proven clever enough to carve out a socio-ecological niche that elsewhere in the world is filled only by Honchkrow and Man.