In the past, before the EU single market and widespread free trade agreements, a country would simply raise a customs duty when another country would overly sub

In the past, before the EU single market and widespread free trade agreements, a country would simply raise a customs duty when another country would overly subsidize an industry. Or they would raise the customs duty merely to protect their domestic industry. Or because they don’t like that country for some other reason. A large purpose of the EU is to remove those trade barriers to make the economy more efficient. Of course some countries figure out how to take advantage of the single market using regulatory arbitrage, quickly entering a race to the bottom. Thus the EU is becoming the regulator in a lot of (non-tax) areas to prevent this. This is just the next logical step in this regard. It’s worth noting that any EU rules on taxation are decided with unanimous consensus. No country here has to do anything against their will.