Quoting a bit more from the Sfakia forum (apologies for encouraging cross forum posts) it does seem that they are applying some sort of reverse logic - reduce the tax and collect more !!:-
Samaras noted that he reached the decision regarding VAT at cafes, bars and restaurants, following discussions with business groups, chambers of commerce and store owners. He did warn, however, that store owners must issue receipts because if tax evasion persisted the tax would be increased again. If the measure proved a success, however, more tax reductions could follow.
This certainly doesn't suggest a reduction of prices to the customer !!