Greece has the lowest amount of government/private debt compared to other OECD (Organisation for Economic Co-operation and Development) nations at 235% of GDP. Government debt at 127% very high and corporate/household debt at 108% of GDP. Greece's black market is 27% of GDP highest of all OECD nations according to the IMF. Due to widespread tax invasion and "corruption." Average is 11% for OECD nations.
To bring the reins in on such a prosperous black market is preposterous and can only hurt their economy even more. This plan is seen in nations across the world. In times of high government/corporate debt politicians and their lobbyist will do anything to squash the competition.
If the black market is embraced by more people in Greece it will flourish and government will ween itself away kicking and screaming to it's death. But individuals who live in the political designation know as "Greece" will have two chooses get off the dole or suck the parasites dry in turn suffering inflation.
In reflection this does not seem likely normally the armed fraction hold on to power and the black market goes deeper underground. But when it is left as the only feasible option for the people it serves it is a market that will grow. Lets watch and see who wins.