Force = mass × acceleration. The larger size of the tablet means that if it fails at an angle where the glass is subject to the impact, the force will be greater. It's possible that tablet glass is designed to withstand a larger force to compensate. I don't have any info on that, anyone has any insight into this?

I also managed to drop my iPhone without it getting a scratch. It does not prove anything, though. Glass is a fragile material and seemingly similar shocks can have very different results. AFAIK most of high-end smartphones use the same gorilla glass.

There are different revisions of the Gorilla recipe, with different tradeoffs.

The 5X in particular also made a bunch of other decisions that helped the glass survive, like having the frame raised slightly past the glass, so that the frame would absorb the impact rather than the glass itself.

I had a Nexus 4, with a glass back and I dropped it and chipped it early on. Since then I use a case, but I've never broken a screen for whatever reason.