I do virtually ALL of my own vehicle maintenance....not only because of the "games" many car shops play, but also the cost. About the Only time I've gone to a shop, in years, was last year when the water pump on my old Dodge Dakota started making screeching noises. That's more of a job than I can handle. The local Dodge dealer wanted over $1000, but my neighbor told me about a local garage. They replaced the pump, the hoses, thermostat, flushed the engine and installed new anti-freeze for just a little over $400...and no problems since.
Newer cars, with all their technology, are a real source of customer rip-offs. Unless a person has an expensive "code reader" there is no telling what the real cause of many of the electrical problems might be. Many of the major auto parts stores have good readers, and will test the car for free. If a person just goes blindly to a dealer, they can easily be roped into paying hundreds of dollars for the replacement of a $50 part.
I have the factory repair manuals for my car, truck, tractor, and even riding lawn mower. If/when a problem occurs, I can do my own research, and almost always fix it myself, for pennies on the dollar, compared to what dealers/shops charge. About the Only routine maintenance I never do is a transmission oil/filter change....a massive mess to drain the oil, and a PITA to remove/replace the transmission pan and filter. And then, I "wander" near where they are working to see that they aren't screwing with something else.
I feel sorry for those who have no mechanical skills/knowledge. They are prime candidates for the rip off artists.