It's worth noting that mirror sites may sometimes not be enough to solve the problems of users from certain jurisdictions. However, it's good that Betfury is loyal to this and is one of the few gambling platforms that openly states that the use of VPNs isn't prohibited.
Mirror sites don't have too long existing time and sometimes a casino must migrate previous mirror site domains to new ones. It's correctly that mirror sites are created to bypass kind of regulation nationally and locally so those sites don't resolve root causes.
Users must be aware of this legal issue and know how they are doing as well as possible legal issues on their sides too. An online gambling business can continue its operation with main site and different mirror sites but a person who lives in a nation that considers gambling as illegal can have big troubles with government and some agencies in that nation.