What happens when the reason for taxation is forgotten

In Greece, austerity measures (paying off foreign bank debt) has led to:

"Very quickly: some of you will have seen that Greece’s tax revenue from VAT collapsed by 18.7pc in January from a year earlier.  Nobody can seriously blame tax evasion for this. It has happened because 60,000 small firms and family businesses have gone bankrupt since the summer."  (see here)

Greece is in terrible shape.