Most money changers in Thailand exist solely to convert other currencies into Thai baht and are only capable of the reverse if they happen to have the funds on hand.
It is not rocket science, It is just plain silly to think any (especially independent) money changer will have anything other than EU or USD around, if even that. I can imagine seeking out any real amount of CAD, NZD, for any other currency without calling ahead.
but then I wouldn't dream of changing most currencies except their native country. I'm more likely to travel with USD for contingencies and change that locally if unable to withdraw local cash directly.