Jeremy, in France the retail prices for both paper and ebooks are fixed by the publishers - this is actually an obligation under French law, though the retailers are allowed to apply a discount of up to 5% at their discretion - at least it's consistent!
In the UK, publishers are not allowed to fix the retail price of paper books (the Net Price Agreement was ruled anti-competitive and illegal) but for now some are getting away with agency pricing for ebooks...
Edit: I don't know about other EU countries, it would be nice people could post what the legal position in their county is