Online gambling is not easy to detect by the government, they continue to operate or partners in other country that are allowed to operate gambling businesses usually business minded people knows what to do in scenarios that they are ban. There are tons of gambling sites now. I wonder if its ban in their country too.
At the bold, it will be more illegal if the owner of the sites is in the country where the ban is effective but claims it is online just because they think the government can't detect them.
They might be lucky to get away with it in under developed countries with less effective technology but in develop countries with heavy technology like China and the others, catching them is quite easy.