Recently finished "Rise of the Warrior Cop".

[A HERETIC I AM]

4. It is and it isn't

This is not a "hive mind" of various police Depts across the country all having the same military build up thinking. It happened too fast.

No, not really. The first SWAT team was formed shortly after the Watts Riots in the late 1960's. The explosion of SWAT teams occurred in the 70's and 80's facilitated by the idea of "Hey! They have one, why don't we get one?"

The answer to your question is no, he doesn't address who is pulling the strings (if anyone) but there aren't really strings to pull. The "Hive Mind" you seem skeptical of most assuredly exists and has existed for decades with police departments.

Not to give too much away, but Balko does go into some detail on the development of SWAT teams and how they are now mostly used for non-violent, victimless consensual crimes, primarily drugs. He talked about one of the highest profile cases in recent years where a team could have done the most good but did bugger all - the Columbine HS massacre. They KNEW where Klebold and Harris were almost the whole time because kids still inside the building were texting their whereabouts, but the Denver PD's SWAT team stayed outside.

Essentially, SWAT teams are used for easy pickings (low level drug busts) and avoid the kind of scenarios they were supposedly formed to address. It is this military style overkill that the book describes.