Mine are more for turning parts of the system off if I need to.
I don't take my cars anywhere for service, I've had stuff stolen out of 2 of them in the past and the dealers do not care, read the fine print when you have work done.
We dropped off a BMW at a dealership, put the keys in the night drop box, in the morning we get a call wondering if we dropped the car off with the radio missing. Someone had destroyed the dash to remove an aftermarket radio, funny thing is, they used the key to open the door because there was no forced entry, so it had to be an inside job. Dealership refused to cover the damage, we had to claim it on our insurance.
Another time I had a car in for paint at a Ford dealer, a bunch of stuff was stolen out of my car, the manager showed me where I signed the work order and it says they are not liable for lost or stolen items.
So yeah, no one works on my cars, if I can't fix the problem myself I sell the car. The 2 year free maintenance you get with some new cars, I never use. Car leaves the dealer they never see me again, even for recalls.