I agree, let's look at the numbers. ~ 300 school shootings in ten years averages out to 30 a year. There are about 100,000 schools in the US. That's a risk rate of 0.03% per school per year risk. Considering that very few people within a given school die per attack, this means that your risk of being killed in a school shooting is basically negligible. Further, your article talks about ANY shooting on school grounds including gang shootings, domestic violence (adults), and accidental firearms discharges so A. almost certainly incidents will be clustered and a middle class school in some random place like what's in the article will have far less overall risk, and B. the actual number of real shootings of the kind that would make the news is far less than 300 over ten years.

The risk of being involved in every other incident class I listed is higher, so that is where we should be focusing our efforts because ultimately a death is a death regardless of what people are scared of. This is basically the terrorism problem: terrorism in the US is this big scary boogieman until you actually look at the data and realize that there's very little terrorism. The school shootings make the news precisely because they are very rare and surprising (and because some media outlets have readership that is in favor of strict gun control so it will play well).

If you want controls to stop school shootings anyway then why not just put in place general healthy population controls: stop bullying, keep a cop visibly on school grounds to deter criminality, engage with parents, and create a healthy environment for learning. All of that costs basically zero dollars and would likely do far more overall good than these silly, expensive, and invasive surveillance systems.