Couldn't sell her potions because of the difference in performance, when the difference was significantly better? The real reason is that they couldn't disturb the market. There would be a constant demand for healing potions, so there's no way her potions wouldn't disappear in no time, but apparently their bureaucracy is so stiff they can't charge more for potions of 50% higher effect. Thus if they sold them as normal potions for the same price, soon everybody would only want those 50% better potions, it becoming the new standard, and the older regular low-grade potions would suddenly be inferior potions. That would cause problems for all the other potion makers. At this point even a child would say just make her potions a bit more expensive, but apparently it's no can do because of reasons.