Consider this, when broken down to its most basic components, the vast majority of traditional self-defence courses only teach defensive responses to an attack once it has begun.
I am of the opinion that’s not only a bit late, it’s also certainly not enough to survive a Mass Casualty Event in these days and times. In light of that, I have found that Reality-Based Self Defence (RBSD) systems take things a bit further by teaching pre-fight tactics such as: creating safe distance; using non-aggressive body language; reading pre-fight indicators; and applying verbal de-escalation techniques. Yet all of that is still not enough to effectively survive a terrorist attack in a public space, especially if you’re with family or friends.