Departure Tax

Recently, I went to Malaysia with my wife, who is an Indonesian citizen. We were informed at the airport that she would have to pay a departure tax of Rp 250,000 just to leave the country.

Indonesia is the only country that charges it's citizens a special tax just for the privilege of going abroad. Could someone reading this please explain what purpose such a tax could possibly serve?

KEVIN J. DUNPHY

Bandung, West Java