Another way to view the medieval approach to land is that it was tied to the people living on it. You bought political boundaries, and the people on the land were bound to it. In one sense you now "owned" the people as serfs, and as another you now had responsibility towards those people.

It's also worth noting how integral Monasteries were to society and provided many of the essential services (from medicine, education, diplomacy etc down to beer and bread). So the "getting in trouble with the church" was actually a stronger mechanism than you would think as they had a large presence and were prescient to common life.