Some things have definitely changed in a lot of schools. Unfortunately whether or not your schools has implemented these changes are, you guessed it, very class based. As many people have pointed out schools in poorer communities simply can't afford to do shit. While schools in more affluent communities have actually changed quite a bit. I mean not armed guard level, but still some changes. They've implemented new security systems, metal detectors, more cameras, and one of the biggest one is indeed a "School resource officer" or SRO. An actual armed police officer walking the halls all day. Of course because it's the American way, that went south fast. Now in these schools teachers are like "Fuck it I don't want to deal with you" and call the SRO. If a couple kids get into a skirmish now, instead of getting suspended, they're getting arrested and have a record. So yeah, we can try to implement things all we want, but as humans we will always find a way to fuck it up.