I think the EU's perspective is that they are one market. That is essentially the biggest advantage of joining the EU, the trade agreements that effectively allow you to do business across the whole EU.Doesn't seem like a good decision. Prices should be tailored for the market, otherwise the publishers will just raise the price everywhere, screwing everyone.
It doesn't really work that way in practice, however. When I was in Amsterdam, Netherlands, for example, hotel rates were 3x higher than Estonia, both of which are EU countries.