To be provably fair it has to be provable and any of its members can verify it. There is no probably fair casinos those are probably scams every online gambling website that is successful is provably fair.
the question is where you put the emphasis on the term honest. If the games are fair, but a casino does not pay out, then you are still dealing with an unfair casino, while the technology and game technically are put together correctly. It is a combination of both for the total understanding of honesty.