Okay, you start a company that has quite of bit of real estate. You have some break-ins, unruly customers, thieves, harassers of women and other creepers, etc and everytime you call the local police. They take forever to come and don't do anything helpful other than file a report and remind you that, yes, they are unionized and don't have to do anything for you. Got a problem with this? Call the police union and the mayor's office. Now what? Do you let your investment and customers take on a lot of risk by a handful of criminals or you deploy your own security services? If I ran any company with this amount of real estate, I'd want my own armed guards. It would be crazy to expect the local municipal knuckleheads to do anything but absorb donuts and file reports.

It blows my mind how much pro-police stuff I see on HN and reddit when it comes to discussions of private security and gun law enforcement. The reality is that the police look out for their own, have their own agendas, have their own politics, etc and that rarely fits in with our ideas of law and order.

As far as the "most countries" argument goes, there's no shortage of private security in those countries, they just don't use the term "police" like we do. Not to mention, in the US, gun ownership is trivial, so the ability to shoot up a school or a train is within the means of any weirdo who wants to. Thus the need for armed security.