What does a ‘thin lines’ flag mean?

A couple blocks from my home I saw the two flags shown above flying, but was not familiar with the dark gray version of the American flag with its green, orange, and blue lines.

It turned out to be an expanded version of the ‘thin blue line’ flag shown above, where blue represents Police and other law enforcement – providing a line between order and chaos.

When I looked it up, I found the meaning shown above, adding colors both for the Military and Search & Rescue.    

But why stop there? Others will indignantly retort that Firefighters (Red) also belong on any flag. Why isn’t there a brown line to represent the Water and Sewer Workers, who bring the water we need to drink (and make the earth bloom) and take away the sewage?  

The Thin Blue Line flag came from Wikimedia Commons.