I understand that ceramic shield glass is not scratch resistant and iPhones are more prone to scratches, and it's not rocket science that it’s much easier to solve the scratch issue with a screen protector. Screen protectors nowadays are really good applying hasslefree.
But my problem is different. I don't have any scratches on my screen. I have a crack out of nowhere even with the screen protector.
First thing I did when I got my new iPhone, was to slap a screen protector and then put in an Otterbox Defender Pro.
Still after less than a month I noticed a hairline crack. No idea when or how I got it. It's a fracture that run across the surface of the screen which is thin. Unlike scratches, you cannot feel the hairline crack with your fingernail. Unfortunately I didn't continue AppleCare+ at the end of my 7-day complimentary period.
Please note that Shatter resistance and scratch resistant aren't the same thing.
Scratches aren't covered by AppleCare but cracks are, which is why they opt for crack resistance over scratch resistance.