I don't know that I can be of any assistance to you paranoid people, BUT, if I had so little trust I would find some new service people.
I guarantee that I know know more about how to handle most of your cars than you do. Do you absorb the release of the emergency brake with your left foot when pulling the knob, do you protect the door striker spot welds by always catching the door before the end stop, would you at 6'4" 270lbs sit in the seat the way you got it to avoid stressing worn seat motors/mechanisms (would you know when that might be useful), WOULD YOU KNOW HOW to stress a motor to solve a customer complaint without hurting the car. I am so gentle with a car that I change my hand position frequently on the steering wheel as to not wear it in one spot.
It is much more likely for a customer to tell me to fix a misfire at 90 (and for me to decline) than for me to drive a car more than 75. And with proper technique I will fix that car without going 90.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician