[Nepenthe]

Mahira-Michelle,
If it is anything like other countries I've been to, they are concerned that they won't be able to exchange it for their own currency, or have it accepted by others. Once everyone thinks this way, no one will take a worn bill. This happened to me a lot in Peru - a slight rip in a 20$ and they won't take it. I ended up trading some friends when they returned to the states before we did - I gave them 2 ripped 20s in exchange for Peruvian soles.