Your analogy does not quite work. And even though I may be an electronics engineer I do not know the fine detail of how my electric car works. I know it has a motor and a battery. But, to use it effectively and safely all I have to know is how to operate the controls. I don't actually need to know how the motor driver works or how to fix it.
Using linux has seemed to me to be very much like being a car enthusiast who is also a mechanic and can fix the car that breaks down often by the side of the road like a friend I once had who is into old cars and prides himself in the fact that he carries so much stuff around in the car that he can fix most things by the road. I would not drive a car that required so much hassle just to get from A to B.
I still don't understand why one distribution is based off another as I do not know in detail what goes into one. All I know is that there is all of this open source software and it gets bundled up with the linux kernel and the desktops that visually hold it together.

