The EU already severely regulate the market http://en.wikipedia.org/wiki/European_Commission_roaming_reg... In fact it was sometimes cheaper to call on roaming then to call for the price-per-minute after you use up all your plan. Not to mention the data
I never really understood, that's just a pay as you go sim from a big player, yet it is cheaper to call a Spanish mobile in Spain with my UK mobile than the Pay as you Go rate from the same operator in Spain.