Scientists have produced an oxide glass with unprecedented toughness. Under high pressures and temperatures, they succeeded in paracrystallizing an aluminosilicate glass: The resulting crystal-like structures cause the glass to withstand very high stresses and are retained under ambient conditions.
People know brand names. People don’t own glass testing equipment. People will buy cheap glass for a high price if it has a brand name they associate with quality.
Supply and demand has nothing to do with it.