That's not how Apple works. You'd be given requirements specific to your team and expected to implement them. End of story. You wouldn't be empowered to seek out other teams and fix their stuff (or even necessarily talk to them). It's deliberate and intentional to have very few people with that cross-functional power.
You're right and not right. There were the infrequent occasions when an engineer would be tracking down a problem they were having and end up in another teams framework/code. A Radar would be created, a polite code diff attached and, often, the team would take the patch and roll it into the next build.
