Baba Bara 63b - Buying the Right to Dig Tunnels

Rav Dimi says that when one sells a house and intends to sell with the house the right to build tunnels underneath plus the right to build up higher, he must specify in the sale that he is selling עומקא ורומא - implying that the seller is giving these rights over to the buyer. However, if Reuven would sell a house to Shimon without specifying that he is selling עומקא ורומא then the assumption is that Reuven retains the rights to dig tunnels under the house (so long as it won't damage Shimon), and also retains the rights to build something over the air space (so long as it doesn't extend down into Shimon's property).

It is obvious that whoever we consider the owner of the land underneath the house has rights to build tunnels so long as he doesn't damage the house. We don't allow the owner of the house to dig tunnels since the area under the house doesn't belong to him.

However, the mishna at the end of chezkas habatim (60a) quotes an argument between the Rabbonon and R' Yehuda whether or not someone has the right to dig tunnels under the public domain. The entire machlokes focuses solely on whether or not the tunnels dug underneath the reshus harabim are going to damage the reshus harabim. The Rabbonon allow him to dig the tunnels so long as the ground of reshus harabim is sturdy enough to support a passing wagon filled with rocks. R' Yehuda forbids it out of fear that in the future it may not be as sturdy thereby turn into an obstacle in the reshus harabim. My wife's grandfather, Rav Yitzchok Gefen, (in his sefer Dalyas Hakerem) raises a powerful question: Why is the gemara focusing on damage to reshus harabim? There is a more fundamental reason for not allowing someone to dig tunnels under reshus harabim and that is, he is not an owner. If I own a piece of property I don't have to come up with reasons why I don't want you to build, just the fact that it is mine and not yours allows me to prevent you from building. Just as Reuven cannot dig under Shimon's house unless he has retained ownership over the right to build, one may not dig under reshus harabim unless they somehow purchase the ground underneath, regardless of whether or not they will eventually cause damage?

I would like to suggest that we can derive from here a perspective on determining ownership over reshus harabim. Reshus Harabim isn't viewed as owned by someone else, rather it is viewed as owned by everyone. It is like a chatzer of partners where everyone is a partner. When I am a joint owner in a piece of property I can do whatever I would like, so long as it doesn't harm my partner (either because i own those rights, or because my partner would be mochel anything that doesn't effect him so that i will in turn be mochel anything that doesn't effect me). Similarly, one who owns a property adjacent to reshus harabim can dig underneath so long as his infinite number of partners will not be harmed by it. Therefore, the mishna doesn't focus at all on "ownership" because in the context of reshus harabim he isn't missing ba'alus. Rather it focuses on potential damage that the tunnels will cause because even an owner doesn't have rights to cause damage to his partners.