Any advantages of living in an RV next to your actual house?

That sounds, to me, what is generally taken care of by the city. If you have common areas, that the city doesn’t maintain, it sounds like either the entire neighborhood is privately owned (which would be a different situation) or the neighborhood has reached out to the city and agreed to take on these things themselves, likely in return for lower property taxes.

Again, isn’t that a city issue? If there’s people living in your backyard, they’re going to bump the population of the city, which in turn will add to the budget for the items you listed. Plus, if people are building actual tiny houses or putting on additions (as opposed to just sticking an RV back there), their property value will go up, which means they’ll pay more in property taxes.

I’m sure this isn’t the case for all municipalities, but plenty of them have various laws on the books that make it possible for them to deal with inoperable or abandoned vehicles on private property.