I'm not sure if I remember the situation correctly.
Basically, the military started handing down their surpluss hardware to large and small local police forces throughout the US.
Since having your own SWAT team is incredibly cool, everyone got in on the action and began building up their units.
Now they have those heavily armed, tactically trained, well payed officers sitting around and the only way that the unit going to pay for itself is by getting used. So they use it. A lot.
Is that about right?