Some countries are currently under some restrictions on gambling while others don't, it might seem unfair but every country has a system and a reason why they execute some laws... Another reason why some countries gamble more than others is scarcity, in countries where there are no job employments or ways for Citizens to live a comfortable life you can't expect them to gamble like other countries
Each jurisdiction has their own regulations when it comes to gambling. But very few countries are banning up until now and most of them are owed to their religion. So whether a certain country is very open to gambling or not, what we can't eradicate is the fact that humans are born as gamblers. So would be hard to totally ban such activity to any human race.