The simple thing is that towns (as the "organizational unit", not the individual plots of land, which are mostly owned by many private individuals/companies) ar

The simple thing is that towns (as the "organizational unit", not the individual plots of land, which are mostly owned by many private individuals/companies) aren't some property that have an owner which can sell them, the municipalities/counties/whatever are determined by the state constitution and government. Municipalities can be merged (or split) in various ways depending on the state, but it's a political decision, not a free market. Also, there's no option for people to "get moved" - you can offer incentives for them to move, but they have the right to stay on their property and to vote for people who promise to maintain their local infrastructure instead of transferring them somewhere else. Furthermore, in the specific example situation you describe, there's a significant expense to NYCity (essentially, buying up lots of valuable land and abandoning it) and no clear benefit for the citizens of NY City, which their government is supposed to represent. Why would people of NYC support spending their taxes on subsidies to some other town's people and explicitly giving housing priority to "others" over the current voters of NYC? The incentives don't seem to be aligned there.