I have got to admit most of the security changes I have seen or heard about at airports seems to me more about feel good than acually making it safer.
To an extent. Most of the more intrusive ones fall under this. Some of the others are actually effective.
is security enough? Maybe. We have not had another attack since then. Something is working.
Post hoc, ergo propter hoc. Attacks were not necessarily common prior to 9/11. Is it due to luck? Increased security? Little bit of both?
Obviously I think it's that last one. But I think that many of our "new" security measures have very little to do with it.
Every few years there has been an attack on a school in this country which might have been prevented or casualties minimized by having a rapid reaction force already trained and in place. Instead, we are whistling past the graveyard taking comfort in the fact that attacks are thankfully rare and playing the averages. After all, the chances are that it won't happen in your town and it won't happen at your child's school but the fact is that it will happen somewhere and somebody's child will die.
Attacks on schools are vanishingly rare. They make huge headlines, but (and this will probably come off as callous) statistically
they didn't even happen.
Put another way, more kids will probably be killed this year by drunk drivers (and I mean
other drivers, not the kids) than have been killed in the last five or ten years by school attacks. If you're actual concern is preventing the premature death of people's kids, there are many better uses of scarce resources.
We cannot prevent all school-shooting deaths, much as we cannot prevent all terrorist attacks, all drunk-driving deaths, or all deaths from negligent discharges. The question is how much effort it's worth to try, and whether that effort could be better spent elsewhere (with a greater number of lives saved).
As regards security guards, a single guard with a flashlight and pistol will stop a majority of attackers who aren't willing to risk death (and nearly all that aren't willing to take a high risk of imprisonment) for their goal. Two or three similarly equipped will stop a majority of those that remain. It's a situation involving diminishing returns. Once you start getting into the extreme cases of people willing to risk death and come heavily armed, even a similarly heavily armed team may not be enough, and will be extremely expensive in the 99.9999% of cases where they are not needed.
I think perhaps arming (say, pistols) the dedicated security personnel for schools that have them (my school had four, for instance) isn't a horrible idea...but the taxpayers probably wouldn't be willing to foot the bill for the training and insurance that would be necessary. Taxpayers barely want to pay for teachers and desks. Especially considering how rarely it would even be needed.