It's also because the Japanese govt does tightly enforce copyright laws. The best place to find unlicensed stuff is in specialty collectable stores, not regular stores. A lot of Japanese fans refer to 3rd party items as "Knock Offs", or sometimes "Chinese Knock Offs." fwiw I did pipe up and said that 3rd party items aren't the same as KOs. But yeah, in my experience Japanese collectors don't discriminate between KOs and 3rd party items much... it's all the same to them (re: anything unlicensed = KO).