Why does it have to come to this?

https://www.wkrn.com/news/local-news/nashville/armed-man-dead-after-being-shot-by-security-guards-outside-downtown-nashville-club/

In most countries Security Guards do not carry guns, but they are assaulted at work in every part of teh world, everyday. So what system is better? and why don’t security guards have better means to protect themselves?