Well, when the homeowner wants to hang a shelf and his nails keep getting bent, he's just going to reach for a drill anyhow
Well, homeowners need to understand that when their nails don't penetrate and only get bent, that they are in fact hitting protective metal. That there's wiring or pipes behind it that could get damaged. And that they must give up on that spot, and nail elsewhere. And also not to use very long nails that they might happen to have a supply of...