When I took out a couple of deer the guy told me that when they deal with an insurance company there are strict rules they have to follow. For example they must buy the parts from approved vendors, instead of visiting a junk yard. Labor rates and hours are fixed.
He had a pretty cool app to work up the quote. He key whacked my VIN and up popped a schematic of my car. He clicked on each section of the car and got a list of all the parts, He tagged each one "OK", "Repair", or "Replace". When he was done it listed all the parts he had to get, the number of hours he was authorized to spend on the repair and even an estimate for the amount of paint. He entered my policy number, clicked "Send" and within a few minutes had the authorization. The quote was not an estimate. That was all he was allowed to charge me, unless he uncovered hidden damage, in which case he's have to run the app again so it could calculate a new quote.