In case it's not widely known, take this as an opportunity to look at the FairPhone http://www.fairphone.com/ that seeks to address exactly this problem.
Full disclosure: I once worked on a part of FairPhone's webshop.
The other issue is that Fairphone has produced 60,000 phones, but Apple has made 700 Million. Can the Fairphone solution scale 10,000x? How does the co-ordination of inspections & unions change if you increase it by 10,000?