I applaud the basic premise of your letter. However, when you are working on your OWN STUFF, there can be a significant impairment of your objectivity, your patience, and yours and your family's emotional well-being.Basic premise for me: Why pay someone that barely made it through high school to perform repairs that are not rocket science - when you were smart enough to get a PSU engineering degree and work in the technical field? It's a nice luxury to let someone else do the work, but a significant money saver to do it yourself, especially a job like brake pads & rotors.... Especially when there is youtube to get you started.
If you change pads and rotors for a living, and you fail to get it done right, worst case there is a delay in the customer getting his car back. When you are doing it under your own shade tree on your own car, you could find yourself without transportation if you F it up. Stakes are raised automatically.
I never saw a mechanic throw tools when he was working on my car, only when he was working on his own.
PS---wait until your wife says, "I TOLD you we should have taken this to a mechanic."