Radley Balco, doing God's work in covering yet another botched SWAT raid

Radley Balco reports on another yet another isolated incident in which a SWAT team busts down the wrong door. Miraculously, no one was hurt in this incident despite the fact that shots were exchanged between the terrified victim and the well-armed police force. Balco really nails the kicker:

The catch-22 comes when the suspect, like Mr. Khang, or like Cory Maye, or like Cheryl Lynn Noel, justifiably feels threatened and acts in self-defense. Then "we need the element of surprise," dubiously morphs into, "They should have known we were the police."

If the point of a door busting raid is surprise, how is an innocent person inside supposed to know that the masked men storming their home are actually police? Balco has chronicled hundreds of these botched raids and his reporting is by no means the end of the story. The only argument here is that these types of SWAT raids should be rare- far less common then they are today. If you reduce their number and frequency you'll have less of a chance of a tragic mistake. For those who would defend these tactics as they are used today (and would therefore write off the innocent victims of such raids as acceptable collateral damage) I would have to ask this- where is the evidence that such raids are needed and where is the evidence that such raids actually prevent more harm then they cause?