Just curious as Aldmer / Altmer were the first to use glass for armor.

I guess it's possible

Huh. Never thought about that. Perhaps there are a lot of malachite ore veins in Summerset? Maybe some magic that can simulate volcanic activity?

Or maybe Bethesda just didn't think about it.

Here is the lore article about raw glass/malachite ore on UESP:
http://uesp.net/wiki/Lore:Malachite


It mentions that, while malachite is mostly found in Morrowind, it can also be found in Skyrim. Although it doesn't specifically say that it can be found in the Summerset Isles, I'd bet that they do have some sources there. That said, every other bandit had glass armor in Oblivion (exaggeration, I know) and there was no evident source for it, so who knows.

Lol, this is probably likely