In a way no, they aren't scarce, they're just poorly spent. Again, I'm talking about a reallocation. If you have a budget split into two areas A and B, A having 60% of the total budget and B needing more than its 40%, I think it would be worthwhile to really look into perhaps lowering A's percentage and raising B's. The spending overall wouldn't change.
Here are some random thoughts about the situation:
There are many schools in my area (Dallas/Fort Worth, Texas) that have lost teachers because of cuts of income from state. Hiring new personnel for security is not an option.
There are ten different entrances to the building that I am in. Additionally, students have to travel outside the building and across a parking lot to get to the athletic field. One or two security personnel cannot cover an entire campus efficiently.
Some of our janitors don't speak English. That could be a problem in an emergency situation if they were the armed personnel.