The point is that the government maintains an entire system for tracking, resolving disputes, and enforcing ownership. Think about who has the final say in a dispute over whether you own your car or your house or your company. The government adjudicates ownership disputes and then enforces that adjudication via people with guns.
It’s easier to notice this system if you imagine the counter-factual: if you lived in a failed state, and you wanted to keep your your home or car you would probably need to hire some guys with guns.
(When you think about it this way, you notice that the “value” of the government’s “service” is much higher for people who own a lot rather than for those that own a little.)
Only 42% of US households own at least one gun. Which means at least 58% of households depend on police for protection. Moreover, having just a gun is not going to be sufficient and you will need other forms of protection offered by police and judiciary. Finally, just having an effective property rights protection and enforcement system deters a lot of crime. None of those things are available for free and property taxes are an effective way to pay for them.
Case in point, in 1986, Michael Lee Platt and William Russel Matix went on a crime spree in the Miami area. They started by murdering a man at a shooting range to steal his firearm and car. They then tried and failed to rob an armored car, murdering an armed guard in the process. Next, they robbed a bank. After a couple months off, they robbed another armored car, during which they stole a guard's rifle and murdered him with it. A couple months after that, they robbed and attempted to kill another man at a shooting range, using his stolen car in a bank robbery a week later.
All of the victims these criminals shot were armed, which did not dissuade them from initiating attacks. The armored truck guards were presumably trained, but not sufficiently to defend against attackers whose opening move was gunfire.
The classic example of this differential response was in 1992, when the LAPD staked out defensive positions to protect the mansions owned by wealthy white political donors in Hancock Park, while Koreatown burned with immigrant shopkeepers left to fend for themselves by forming armed vigilante militias until the national guard was deployed and restored order.
Of course, there are limits to the protection they provide- you can always buy more.
I would make a strong delineation between the adjudication of property rights and the enforcement of property rights. Those are two different things, and it has ever been the case that individuals frequently must act in an enforcement capacity. Potentially, if you tried to take someone's land, they will shoot you. That is enforcement. Adjudication happens when a judge says they were in the right.