In this particular case, it's quite simple to see and think that there is drug activity going on in this house. That is pretty clear by the back story. The police (from what I can tell) have done nothing wrong here, just serving a warrant. Let's go with a what if...What if, there was actual gang activity in this a 'safe' house. The police knock on the door, yell Police, open the door. The gang then has time to arm themselves.

Based on this and so many other 'anti-police' threads, where it doesn't seem like they can do no right...maybe America should just say fuck it. Disband all police forces and let things go as they go. Let's let America burn it's self to the ground.