In the country where I now live there is no need for underground casinos, because all casinos are legalized. The fact is that there is a large country nearby where all casinos are prohibited.
And, of course, nothing prevents citizens of this big country from turning on VPN and going to online casinos, but I know that many people do not recognize online casinos, but only love physical casinos for the atmosphere of these establishments and the fact that you can communicate with people there.
But at the same time, I know quite well that small casinos in small towns are quite different from large casinos in the capital.