There are several factors that contribute to a casino deciding to whether and who to ask to verify his or her account, just like you mentioned about casinos knowing when a user is making use of VPN possibly as a way to hide their true ip address, specially when the gambler is gambling from a restricted country, such a user is likely to trigger the kyc verification system faster then other persons who are not using VPN to play.

And also myself, my Bc.game account is also still unverified, I am not a very frequent gambler though, but I definitely over time have played alot on this casino, withdrawn some nice sum of amount of money which ordinarily should trigger the kyc system if it was on any other random casino, but that didn't happen on BC, this goes to show that maybe Bc is not really heads-on on collecting customers data, but care more about giving customers the satisfaction they need.