Time and time again: They’ll gladly act when they can use overwhelming force. But when they are up against a similarly armed individual (ar-15 firing similar rounds to the military, body armor, etc), they cower in fear. Sometimes SWAT will actually act, but usually in situations where they can more or less level the building with tanks and explosives.
Its one of the best arguments for gun control. Because if we didn’t have ready access to assault rifles that were literally designed for military purposes and that fire one of the nastier rounds in existence*, then maybe “a good guy with a gun” would have any effect at all.
And just in case anyone thinks bump stocks or illegal modifications will let them stand up to the army: the army has “real” tanks, air support, drones, and a lot more explosives per soldier. You won’t stand a chance and, if anything, a concealable pistol chambered for one of the small caliber/high velocity rounds is more effective for a resistance force.