A household is an open system. It is possible for a household to increase its net revenue without incurring costs. For example, if I get a new job with higher pay, the amount of money in my household has increased.
Countries (even countries in economically integrated Europe) are closed systems. Increasing the revenue to one sector results in losses to another. In this case, the Greek government can increase its revenue by increasing enforcement and raising the tax rate. However, that results in a cost to the private sector. People paying more in taxes have less to spend on other things, which lower economic activity and lengthens the recession.
As an aside, this is why I get very irritated when politicians use household/business analogies to model national economies. The two are different in kind, not just in size, and trying to compare an open system to a closed system leads to serious errors of judgement.
I don't think countries are closed systems, since they interact with the rest of the world. Countries can increase revenues without increasing costs. Suppose a country figures out how to get fusion to work: decreases electricity cost, increases revenues from sales of fusion plants. Or they talk to other countries about how to grow more/better crops; assuming they weren't at 1st world yields, there are many things that are cheap to implement that produce more money.
But isn't this a problem exactly because countries are not closed systems. They trade, borrow and lend money to each other. There is an interest rate involved. That seems like an typical debtor-creditor relationship that one might have with someone.
Countries (even countries in economically integrated Europe) are closed systems. Increasing the revenue to one sector results in losses to another. In this case, the Greek government can increase its revenue by increasing enforcement and raising the tax rate. However, that results in a cost to the private sector. People paying more in taxes have less to spend on other things, which lower economic activity and lengthens the recession.
As an aside, this is why I get very irritated when politicians use household/business analogies to model national economies. The two are different in kind, not just in size, and trying to compare an open system to a closed system leads to serious errors of judgement.