So yes manufacturing issues and not own mistakes.
So out there in a real world you will find from 50 people 20 with scratch and probably none with broken screen.
In my last 4 years i saw only 2 broken phones and i asked that persons how can they use those phones like that..but the answer always was "today/yesterday i broke it and tomorrow i will replace it". So bottom line phones that breaks are replace next day,simple as that but from iphone 6 you will never see a non perfect screen because scratches will be out of the questions
I give up. Show me something that backs up your claims. I can't show you any that back up mine as I don't see people complaining about scratched screens. I have seen dozens of broken phone screens, it's hardly limited to the iPhone. The mall kiosks here do a good business replacing broken screens, but whatever.