>To me the upsetting part is that these kids must feel unsafe / monitored.
Many larger schools have their own police officers, because they have to. My fiance is a high school teacher and just out of her classes in the past 2 months she's had one student arrested and expelled for bringing a firearm to school and another for bringing nearly a pound of marijuana (in a state where it is illegal at the state level) to school. Earlier this year they had two students expelled for having sex in a classroom after school while filming part of it with one of their phones.
Even from 1998-2002 we had school police. We had multiple people dealing marijuana, MDMA, LSD, and probably other stuff I wasn't aware about. We had several students investigated pre 9/11 for threatening to deploy pipe bombs at the school, we had more than one overdose (all MDMA I think), I'd watch a girl in study center once or twice a month sit there and rub her face the desk or her binder with pupils the size of saucers, we had students drinking on school property in the middle of the day. We had at least one student that I know of on an ankle monitor for most of high school. If you went out for a sport you would be drug tested regularly, without notice, pulled out of class at random and people would occasionally fail. While we had students doing FFA and being volunteer junior firefighters after school we also had people with extensive juvenile records and children.
When I was in middle/high school 16-21 years ago you could buy drugs/pornography/bootleg cdr movies/alcohol/other things that were age restricted like ephedrine (we abused ephedrine so much I have no idea how I didn't have heart failure) in the hall or bathroom between classes just by walking up to any number of people. I've found talking to people this is not a unique experience and most of the same is still occurring in high schools right now.
Many schools across the country simply are not utopian dream lands. If I had kids, I'd be 100% fine with them being forced to have clear backpacks and I'd go a step further and suggest they only be allowed to and from their locker upon arrival/departure and not allowed between classes. It's one small step that considerably reduces the risk of a kid lugging a weapon, explosive device, non-personal use amounts of drugs. Sure, I could have hidden a small arsenal and a large quantity of drugs on my person between my hoodie and jnco jeans in high school but a clear (or no) backpack drastically reduces the likelihood of these things being taken to school.