It is not that the casino doesn't want those people on the countries that they restrict but it's just that it is only ordered by them by their license provider or the government. That is what I heard before but that must be true because if they won't obey it, they will also be in trouble and as a casino, they would also want more customers to play on them (if ever), as that means more income for them as well.

There are still casinos that allow a VPN despite having a country restriction. I know and use some of them before though, that is why I know. There are reasons on why they do this and I think this backfires them but luckily those casinos I know are still there, operating smoothly. Maybe they still have measures to detect players that are not genuinely residing on that country where they use a VPN.