The EU was designed with lots of hops that a country had to jump threw but because for political (even idiological reason) those things always gets ignored if they are in the way of the larger planes. Greece for example should never ever have been able to join the EU given the rules that existed and we can see how that turned out.
The EU simply has very little oversight of internal politcs of countries and because there is no way you can be kicked out, once you are in, you can do pretty much as you want. That is, as long as you don't need massiv amounts of financial aid.
