Because ignoring a problem makes it go away
Elected Officials Doing Nothing Is Not Working:
Let's be clear: mass shootings are symptoms of a vastly larger gun violence problem in America that we enable by our inaction and inattention.
OK, so let's treat the symptoms by passing a bunch of ineffective legislation so our money-grabbers in Congress can be seen as doing something other than collecting money!
The actual problems that cause incidents like Columbine will probably never be solved. I doubt Congress can pass any legislation that truly solves this problem at all because they can't legislate some sense into the typical bully, or legislate tolerance into the typical school administrator.