There isn't a "complete lack", I have seen them testing, although I didn't know why (maybe someone reported another player, which anyone can do) but they don't routinely test everyone's gun. They are clear about this though, and above someone comments that "pre-game chrono is largely just theatre" and another says CO2 pistols "don't generally get tested at any sites", even though we all know CO2 pistols are often hot. I have only been to a couple of sites, but I have yet to see any testing of all guns... maybe some do and I just don't know what I am missing...
Maybe it did, but as the incident was nearly 6 years ago now (and at it's heart, I understand one kid pointed a gun at his mates face and pulled the trigger whilst cocking about in the safe-zone, which, without wanting to start a lengthy debate about what could have been done to prevent it, is hard to legislate against), if people are posting their reviews based on the poor safety before that time, it is probably hardly relevant now and perhaps they should preface their review with the fact it is based on a six year old experience! I was there weekend before last, and I was impressed by their safety now, even if it is due to an accident that happened nearly 6 years ago.