Greece is a country of small shop owners and wealthy billionaires but few workers in corporate systems where they get paid by a twice weekly check like in most of Western Europe and the USA. The Greeks have also been ruled by many tax greedy empires and have learned to hide wealth as part of their DNA. They won't dutifully pay taxes like a German or Scandinavian (who seem like a very servile people and seem to obey the govt as if it was God).
Greeks can't be ruled easily. That is why they invented democracy because ruling them in any other way just did not work. Even the Romans gave up trying and made the Greek city-states autonomous for the most part.
Through years of rule by Romans, barbarians and Turks the Greeks have learned to avoid the tax collector in ways limited govt Republicans can only dream of.
Greece's current revenue collecting system - created to be inline with the policies of the EU is not suited for that country.
Greece is better off adopting a sales tax approach to revenue collecting. It can even have different percentage values for off seasons to boost slow downs. For example, charge 15% sales tax in July and August during the high tourist season and charge only 10% tax January and February. The rest of the months can be at a 13% level.
This would encourage vacationers to book hotels and tour packages in the winter and it is good for business because they will arrive in the summer and spend money to be taxed at the higher level. It will also allow people to do more business in the off tourist season - I can envision property sales happening more in winter than in the summer for example.
The national sales tax instead of an income tax would encourage thrift and savings as well. Inheritance of property would not be taxed as it is now.
Would this boost revenues? We would not know until it is tried. Because Greeks cheat on income taxes and make most of their money in untraceable cash - the sales tax - with a paper receipt - is the only way I think you can get Greeks to pay taxes in a way that is somewhat traceable. Russia had the same problem with tax collecting from a population not used to paying taxes. They adopted a flat tax. The Russians also earn income from nationalized raw material exports. The Greek raw material export is really its tourist sector which is still a gold mine for them.
In any case, under the current EU euro austerity system such experiments are not possible.