It's not just a matter of buying a battery and using some tools the average person has on hand. A whole kit of specialty tools and parts needs to be ordered to facilitate the repair. Apple's own repair kit is the most extreme form of this, where they ship 70lbs of tools, which would be comical if it wasn't so sad.
Do you also consider yourself incapable of jump starting a car because you might have to look up instructions first?
I know plenty of people that would never even consider jump starting thei car. However are also quite happy with poppping open a battery cover and doing a simple swap like any other battery powered device.
There's also a difference between not wanting to do something, and not being capable of it.
Many milions of people are scared by things such as red and black wires and wont touch them with a barge pole.