The section of the wikipedia article on qanat's in Iran is huge (3700 words) in general, and especially compared to the sections about qanats in other countries. Between that and this video on qanats in Iran; what makes them so much more important/studied/etc.? Is it just that they were invented there?
Well probably not just, but Qanats are persian tech and spread from there, even today the majority of qanats (both historical and extant) is in Iran, with still-active qanats more than 2000 years old. So it makes sense that this is where they have the largest cultural presence, and understanding.