So the problem with free riders is supposedly security will be under produced because of it, right? Even if there are free riders in some areas, I don't think it follows that security would be under produced. Like, even if in NYC or Las Vegas, no citizens specifically buy national defense protection, I think with all of the money invested that national defense would be provided by anyone (shareholders etc) who owns any expensive property (through insurance). You could multiply this scenario thousands of times throughout the USA because of all the private investment in various cities. Once you multiply this many times, all of the sudden an invading army would find it hard to make a lot of progress. What are they gonna do, invade a potato farm in Idaho? Naaa, their targets are gonna be valuable, so it follows that the cities are the only ones who even need it and since people invest there, it will be provided.
Another solution is to "eternalize the externalities". What I mean is that I don't see why defense companies or whatever could not publicize a list of people who do not have defense. Just be like, "yo, free attacks on these people, they dunnn have security!"
Also, on people free riding on local security, in the over all production of security I don't think it matters. Anyone who owns a road or business will provide security, or else they would lose business to safer places. If an area is so safe that security isn't really needed, then the underproduction obviously is not a problem. With neighborhood protection too I see contracts emerging between landlords where either they themselves contractually agree to require tenets to buy security or the landlords buy security as part of home insurance. Or non-landlord owners might join neighborhood associations or whatever, and if someone refuses to buy security, it would be pretty easy to let all the criminals know that certain houses have no protection. But again, even if someone has no subscription, I don't see why they still couldn't call for help and just get charged a higher price or whatever. The amount of security provided would actually be in proportion to crime rates. Say that it is so nice somewhere that no one buys subscriptions, but relies on just emergency help. Well, the police force will be small, as it should be!
Defense and insurance companies also having a lot of money at risk with customers and their own capital (buildings, equipment, etc.) would have an incentive to contractually agree to group up in case of an invasion. I mean, think if you owned some stuff or a company, and you saw some army invading 300 miles to the south of you, then 250 miles, then 200, then 100, getting closer to you each time. I think it is obvious that even companies hundreds of miles away would view an attack on their neighbors as a potential threat. So I think large areas would be covered just by various investors, insurance agencies, and defense agencies agreeing to help each other out for their own good.
Also, when we think of war right now, we imagine how ridiculously expensive it is, well...because IT IS. The insane amount of money spent by the US military is more than the whole world's defense budget COMBINED. What I am getting at here is that DEFENSE spending would be extremely cheap compared to the costs we imagine with war now. Not only is the US maintaining an empire, but the US government is terrible at allocating resources (i.e. they spend a shit load of money without concern). With private defense, it will be efficient and dirt cheap compared to government military. I could see all the major cities defended against invasion for CHUMP CHANGE. What this means is that I think with how cheap it would be, people mooching in itself would not be a big concern. Some people are super cheap sure, but I think most people would pay an extra $10 a month (assuming companies didn't already cover 100%) vs facing the social pressure or even a black list of people declared "free to attack". Defense is SUPER cheap compared to offense, I think even a small town (like my home town of 9k ppl) could afford adequate defense, although it probably would not need "national" defense, but that is impossible to decide, which is exactly why the market is the best way to find out lol!
The final and more romantic answer is guerrilla warfare. This can't be underestimated. Look at history, as in Vietnam, Afghanistan (Soviets and the U.S.), The American Revolution, etc. All of these are cases where average citizens with rifles take on the world super power. I don't see why a libertarian society would be any less motivated than any of the cases mentioned above. With everything said about about insurance etc. providing defense, I think guerrilla warfare alone could defend against an invasion. I am not saying I think it would be the only defense, but I think it alone could do the job. So adding this on top of everything above, the insurance and defense agencies etc., I think invading a free society looks like a giant headache to any potential invaders. Why not just invade some poor country with a government, take out their nation's capitol, and be done? Compare invading a poor country where you only have to take out one city ( to take over their government) to everything I have said here and I think there is a strong case that it would be cheaper and safer to just invade somewhere else.
