makes sense
but that brings a question
how would they know if you are using a VPN to bypass a restriction from determined country or not?
since your true location would be masked.
I dont have enough knowledge to explain about it in more details but I'm sure it is related to security system where casino can detect such activity. Perhaps there are some users who knows how this security system works so lets wait for them if they can answer you with more details.
in reality I'm not sure if it's possible, only in case the user is sharing more geo-localization information with the website, like if the user is accessing from a smartphone and not from computer
if the users access with a VPN shouldn't be possible for the website to tell their country...