Depending on the reservation, you will find plenty of non-members that own property within the reservation.
It's kind of fascinating having these micro-nations that aren't quite nations within our borders, I should read more in to this subject.
Real property within reservation borders is either deeded land or trust land. Deeded land can be sold without restriction. Trust land cannot be sold without approval of the US Bureau of Indian Affairs and/or the tribe.
Natural resources in reservations are usually managed by the tribe. Including hunting and fishing. Some let non-Indians or non-members hunt/fish some don't.
Except for a few exceptions, living on Indian reservations is no different than living anywhere else. Tribe made laws/rules do not apply to non-members -- unless the State or Feds says so. These are usually hunting rules. For example, the Colville Reservation in the State of Washington restricts non-members from hunting large game (deer, black bear, etc.) even if the game is on deeded landed. They can do this because there is a state law that says the same thing.
Also, generally tribes or tribal owned businesses cannot be sued in state or federal courts unless they agree to be sued (same/similar as States and the Federal government). Thus, persons have few rights when it comes to contract disputes, personal or workplace injuries, labor issues, and so on, that involve tribes or tribal owned businesses. Something to think about if one is considering employment or otherwise doing business with a tribe or tribal owned business.
"Tribes possess all powers of self-government except those relinquished under treaty with the United States, those that Congress has expressly extinguished, and those that federal courts have ruled are subject to existing federal law or are inconsistent with overriding national policies."
They retain ownership, but can actually get something for it.
If you're referring to the New Territories portion of Hong Kong, that lease was from 1898 to 1997. That lease expired almost 25 years ago.
[0] https://en.wikipedia.org/wiki/St_John%27s_Cathedral_(Hong_Ko...
https://en.m.wikipedia.org/wiki/Ground_rent
Yes it can hurt resale prospects, the longer into the lease you get. At the same time it can also lower upfront acquisition costs. Something to know when you get into it.
If you think about it, there isn't much of a difference between a 99 year lease and a 1-3% property tax.