I accidentally discovered this when I accidentally dropped it from a high table onto a hard tile floor.

Since then I thrown it on the floor multiple times without even it sustaining even a little chip.

Any explanation? Why would a cheap bottle of perfume be this unusually strong, when I've looking for cookware and drink-ware that is even half as strong without success?

I'm no materials scientist, but here's been my observations in working with glass receptacles and bottles over the years:

Shape is a very important aspect of how strong glass things are. Perfume bottles (or any small bottle) tend to be stronger just due to the fact that they usually lack large, flat-ish areas and the thickness-to-surface area ratio tends to be higher.

For instance, if you drop a small glass soda bottle and a large glass soda bottle, the large one is far more likely to suffer damage than the small one.