I think it's a combination of the responsibilities and the drivers in the system. You could say that trying to regulate the market to have obligatory insurance with obligations for insurance companies but also incentives for them to keep their premiums at an affordable level while also providing for the care of their patients drives them to find the lowest price in the market.
As a result of prescribers' being contracted, when it comes to the prescription of generics according to set guidelines, the parties involved all have an incentive and benefits to keep the financial burden on the system as low as possible. It's a balance—the market balance, you could say.