While I mostly share your point of view - not every horrible event is necessarily preventable short of some extremely draconian measures - I don't think it's ju

While I mostly share your point of view - not every horrible event is necessarily preventable short of some extremely draconian measures - I don't think it's just a matter of throwing our hands up and acquiescing that "Anyone can drive their car across the centerline" for example (and indeed there are sometimes barriers or physical space between opposing traffic lanes). So the question isn't, "how could we have prevented this particular tragedy from occurring, at any cost?", but more "can we reduce the likelihood of an event like this in the future, in a way we're comfortable with?" For example, locking cockpit doors on airplanes is a pretty low-consequence action we now take as a result of 9/11. Not entirely without tradeoffs, sure, but a fairly effective action nonetheless. Air travel in general is actually a pretty great example of making something relatively chaotic considerably safer over time.