Hi, why is the answer: manufacturers charged all authorized distributors the same unit price for products regardless of quantity purchased?

Why not: manufacturers refused to provide the "extended product" to consumers who purchase goods in the gray market?

Around line 10 the passage tells us that a major factor contributing to channel flow diversion is that manufacturers offer quantity discounts that encourage reseller to sell on the grey market. Thus, eliminating this quality discounts should cut diversion. The passage tells us in the third paragraph that manufacturers actually don't offer extended product to customers who purchase in the grey market.