That is interesting, I have lived in three EC countries since 2005, in all of them Maestro either was already the main card, replaced the local debit payment network (as in the UK with Switch) or became part of/affiliated to the local one (e.g. EC card in Germany). I have however heard that there are some differences in Maestro cards issued in different countries, so sometimes retailers wont accept cards from country or bank x - personally I had this happen to me in Switzerland once with all my bank cards at a forex booth! The cards however worked perfectly in the ATMs and in restaurants etc.

I have only once or perhaps twice used my Maestro card in another country and that was ok, however the bank I was with did levy a fee which was rather excessive so I never did so again.