Because there's no active war, and the military-industrial complex still needs to turn a profit.

So the cops are given military equipment, often for free but with the stipulation it must be used within 6 months or returned, so they come up with reasons to do heavy swat raids in full military gear for some guy growing pot in his attic so they can keep it.

This has been going on for about 15 years now, and it just keeps getting worse.

Also they only get 6 months of training, and seem to prefer to hire war vets in many cases, which just confuses the military with the police and exacerbates this whole issue.