> Thus, fixing a car radio may seem prohibitively expensive when compared to the price of the car.
It's very easy to add together a few repairs which sum to more than the value of the car. If you wanted to get a new car from scratch by ordering the individual components and having your dealership put them together, it would have to be at least 10x more expensive than buying one produced at scale.
> If you do it yourself, it's cheaper, but the insurance company won't pay for it.
On the one hand, you have the value of your time in your skill area, versus mucking about with a radio. On the other, you have the overhead and inefficiency of a huge dealer/insurance system. Somewhere in the middle is your local mechanic :) Find a good one and make friends - you don't have to go to the dealership!