Swat should learn to throw a flash into the center of the room
Police work is a dangerous job. Not every house is built the same on the inside. Some rooms can be bigger or something or contain obstuctions. So that flashbang could go far, or it could go short or bounce of a ceiling or some object. Second, sometimes it is hard to get it chose. When creeping around the windows, you might step on an object that gives away your position and lets the badguys know you are here. The victim might get killed, or bullets go flying out the windows.
Second police are peace keepers, not soldiers. They don't have time to go down to the range, train as frequently.
Then you have your rules of engagement, department policies, laws, and trying to keep causalities at a low.
here:
http://www.theguardian.com/law/2014/jun/24/military-us-police-swat-teams-raids-aclu
"military us police swat team"
sounds like the typical liberal English media
"dumb baby killing americans have guns. Many people die in cross fire between police and criminals. Please disarm 3rd world America to bring peace!"