This is the current model. In many places the violence may be out of living memory, but it's generally all very recent.

Just a few years ago, the weekend before May Day, a lawyer was stopped by the police here in Panama. The police searched through their database and found the lawyer had been accused of "economic terrorism." The lawyer was immediately put in jail. He worked pro bono defending the rights of informal settlers who have lived for years in vast areas of land owned by a very rich family. Given the amount of time these people have lived there, some argue they should at least be allowed to pay water and electricity. Instead, the government sends riot police to pull them out of their homes. The lawyer was released a few days later. This is only the most recent case that comes to my mind here in my country. I don't think it is that different in the rest of the world. Ownership of land is tied to violence.

Actually I just remembered a more recent case. After a very rich old lady showed up in TV last year explaining to people how access to drinking water is not a human right, videos came out on social media showing bulldozers destroying orchards in one of the Pearl Islands. They've been doing it since at least 2012. The rich lady's family wants to build some nice hotels there.

Maybe technically there’s a threat of government violence in the background, but that’s pretty far from most people’s consciousness in developed countries.

Can you propose a different model for property ownership which doesn’t require the individual to invest more resources in physical security?

I'm not sure about "most developed countries" but there is still very strong memory of past violence in Great Britain. Some of the tail end of it still bubbling.

On another tack, there are plenty of homeless people in the UK. Can you imagine what would happen to them if they broke into expensive uninhabited properties in London? There would be violence.

I have no idea of alternatives, I was just pointing out the origin of a lot of current land ownership.

Pay the non-owners enough rent to make it their economic interest to respect and protect the ownership

The problem in this case is not land ownership but exclusive political and / or economic system which rigs the game against a certain percentage of a population on all fronts.

If it is out of living memory it isn't current.

If the model establishes a system where the people who are prepared to use the most violence end up with the land, and a couple of generations their descendants still have the land, then IMHO the model is still in play.

You could also argue that as the ownership is codified in laws and the state monopoly on violence keeps the oppressed in check, that threat of violence continues.

"If the model establishes a system where the people who are prepared to use the most violence end up with the land, and a couple of generations their descendants still have the land, then IMHO the model is still in play."

This is not about land ownership. Alone. You are talking about exclusive political and economic systems. In an exclusive system it's not just the ownership of land that is broken - you will find all economic activity is rigged against some segment of the society. Most well to do states are have inclusive political and and economic systems. In these societies land ownership is based on land registration and enforceable contract law - not entitlement of birth and violence.

I warmly recommend Daron Acemoglu's "Why nations fail" as it explains this topic far better than I ever could in a few sentences.

Thanks for the recommendation, I'll look that up.