My, How Things Have Changed! : How Come?

I remember going to school with my pistol in my belt so could work on it during shop class.

When I got into school, placing in my locker where everyone saw me do it, but no one cared! How come?

On my way to shop class, stopped at my locker to get my firearm so I could work on it, as like other students were going to with their fire arms, and again no one seemed to care, as I remember. How come?

The parking lot had several pickup trucks that had rifles displayed in the rear window rack and the trucks weren't locked with the windows down and the keys still in the ignition. No one seem to notice that this might be dangerous or cared. 

How come? It's only been several decades! What's changed and so dramatically!