After 9/11, there were all sorts of changes made in this country in an effort to do everything possible to prevent a terrorist attack like this from happening again. It wasn't just one thing that was done. It was MANY things, from TSA pat-downs/scans, restrictions on what you can take in a carry-on (lighters, nail files, liquids over a certain amount, etc), government-issued ID's, airport security, and more. Not everybody liked all the changes or agreed with them... but most everybody understood why they were being made and have come to accept them. Most of those security measures are still in place today... all as a result of 9/11. Did they really make a difference in terms of preventing terrorist attacks? I have no idea. But there haven't been any more in this country ... at least not on THAT scale.
Can we not look at trying to prevent mass shootings in the same way? Shouldn't we be willing to do MANY things to try and at least lessen these incidents? Yes, we should be doing many things... but we won't. How do I know we won't? Because we've had 23 years to at least TRY... and we've done nothing but point fingers and make excuses.