You need to understand the setup of the European Union and EU state aid law. Part of the idea of the EU is creating a common internal market between the 28 EU m

You need to understand the setup of the European Union and EU state aid law. Part of the idea of the EU is creating a common internal market between the 28 EU member states. For creating a level playing field that is not distorted by state intervention, you have to prevent single member states from giving unilateral advantages to their own companies (ie creating "national champions"). So if member state A gives an illegal subsidy to a company, you could of course fine member state A to prevent this behaviour in the future - but you would not be able to remedy the distortion of competition that already occured because of the subsidy. It is much more efficient to order member state A to recover the illegal subsidy they granted to the company in the first place. It is quite telling that the Belgian government in this case is actually going to appeal the Commission decision - although the Commission decision would lead to Belgium being granted 800 million Euros!