I don’t think it’s generally that. I think when you purchase a smart phone (More specifically, an iPhone) they’re generally very expensive, and you have those who want to take care of it, not just for the resale value, but simply because how expensive the smart phones are to be repaired today without AppleCare. And the majority of smart phones that are used on the market, they don’t have AppleCare. So when you shatter a display, it’s only in someone’s best interest likely to have a screen protector or a proper case to help prevent accidents as noted in above examples in this thread.