I think this is indeed a problem of awareness - and I'm sure you're right that companies wouldn't go out of their way to let users know they can do so - but also one of trustworthiness: I think a lot of people don't trust third-party repair shops because they feel it's sketchy or unsafe in some way. If phone manufacturers were like, "Here's a list of our trusted third-party repair shops and the parts they can fix" I imagine a lot more people would get their stuff repaired.
Yeah, that's surely part of that. There are authorized service centers in major cities, but that's not very accessible for a lot of people. When I got my battery replaced, it meant 2 trips to a 100 km distant city (no same day replacement) which also meant a day without my phone. I could have opted for an unauthorized repair shop, but again there's the problem with trust, these often seem quite sketchy.
