The banking market in europe is not as unified. Simple would have to approach europe country by country. For example, retail banking in italy is nearly ten times as expensive as in the netherlands.
A pan-European, unified solution would indeed be rather hard to do, but even going country by country you could earn quite some money. Start with the UK (fewer i18n and support problems), then probably the countries who are paying for the rest of the EuroZone right now.
There's a study by the EU on this topic: http://ec.europa.eu/consumers/rights/docs/study_bank_fees_en...