When the casino starts asking KYC the gambler who stays in the country where gambling is illegal will learn the difference. No difference at all and he will be banned instantly when they see the documents he is a national from a country that bans gambling.
But because some casino allows gamblers to withdraw certain amounts without KYC, the VPN users are fine.
So that's all? countries where gambling is legal do not have laws or institutions to protect gamblers from online casino fraud? So how does a casino license work if gamblers cannot report or protect their gambling activities?
If the difference is only about KYC, then I think gambling from a prohibited country and not doesn't seem to have a significant difference, and VPN can be used to access gambling sites by changing the IP address