Of course the culture of tax evasion has to end, but all economists, including the respected RBI governor Raghuram Rajan, were vehemently opposed to demonetization as a tool to enforce that. It had a great cost and it had very little effect. I will give you an example. The Modi government invalidated INR 15.6 trillion, and expected a full INR 5 trillion to remain invalid. Besides the benefit of attacking black money, it would've given the Modi government a windfall gain of INR 5 trillion which it could print and spend on its own without the danger of rise in inflation. However, a full 98% was deposited into the banks, which shot down any chance of catching the black market operators. The remaining 2% also consists of legitimate income that could not be deposited due to it being stored around the world.
Who lost? The poorest of the poor who survive on cash. As normal Indians cut down on cash consumption, the Rikshaw driver and the food cart seller suffered.
Btw, the Greece issue was the result of borrowing beyond the country's limit, and not tax evasion.
You had a long time to try out other remedies. Modi had his chance. He rolled the dice.
In Greece nobody pay taxes which is why they cannot repay their loans