For one, there are private firefighting agencies, private security and detective agencies, and private armies. To the extent they are permitted by law, and sometimes when they aren't, the market provides each of these. But let's look at a particular example, that of the police. Though some rich people hire bodyguards, it is certainly true that some funtions that the police perform, like process service and execution of warrants, are a government-granted and government-enforced monolpoly. Hence, the fact that ABC Policing Services, Inc., does not do these things is not a failure of the market, rather, it demonstrates yet again that the market is not even permitted to enter into some realms.
Individuals fight terrorists just like governments do, except that in the case of 9-11 the facts indicate the superiority of citizens. No, it does not.
My example was of the four hijacked planes, private citizens stopped the only one to miss its target
It was not the private citizens who went to Afghanistan, and they could not; rather, it was the U.S. army, which the markets cannot provide. A government is needed for that.
First, these events didn't happen on Sept. 11 and therefore aren't covered by the article (or, the article doesn't mean Sept. 11 literally). Second, the fact that private citizens are prohibited from acquiring tools of military force does not prove that markets can't provide an army, but rather that the government prohibits it. Mercenaries certainly exist, and would be more common if there weren't such a roadblock to them in this country.
[Screening passengers]Here you confuse the failure of the specific means with the very availability of the function. Perhaps, next time you will not shoot from the hip.
The author stated that "only the government ... could be depended on ... to screen passengers at airports." This screening happened, and failed to avert the hijackings. The facts cut against the author's point.
You are the one shooting from the hip.
Please look up the distinction: public goods are characterized by indivisible consumption; that is, once produced, no one can be excluded from consuming them. Police protection, defense, street lighting, and clean air are usually offered as examples.
With private goods, such as an apple, you can exclude others --- those who do not own the good -- from consumption.
There is an intermediate, less researched category --- that of club goods.
Again, I made a statement with regard to public goods; your reply centered on private one. I do not disagree with your remarks, but they speak on a different topic than my post.