This is my concern. Regarding the supply chain, perhaps the (re)sellers are not aware of the goods being counterfeit. Chinese manufacturers have been known to adjust product without informing the brand. Brands don't usually have someone spot checking every item that rolls off the assembly line. These glasses are one-off purchases and I'd assume demand is multiple orders of magnitude higher than normal. Corner cutting at the manufacture in China is where I'd start investigating. Again, more often than not, a Chinese manufacturer (boss) would rather deliver unsafe products and save face then to tell the buyer I can't make them. Especially smaller fly-by-night "factories" that are constantly appearing in the countryside or factories facing a giant surge in demand.
And where do you think that place got their glasses from?