If they impose the tax on gambling maybe their government want to take advantage on the fame of this industry then try to get something from this. But we know how heavy the implication it could possibly bring to their citizen especially if they didn't done any gambling education programs to educate their citizens towards the risk of gambling and possibly make them aware of gambling addiction effects to their selves.
I think there's some part that corruption play on why they decide to do that. So lets do hope that people are aware on each decision done by their government then see if what they do is contributing somethings especially for the growth of their country. But if nothing happen then I guess only those corrupt officials are benefiting for what taxation they do and let those people burn in fire on the implication brought by what they allowed to operate in their country.