Even for sites that do promote themselves as provably fair, I wonder how often people actually check to see that the results of their game rounds are as they should be. I wouldn't have a clue how to do it, and even if I did, I probably wouldn't bother. I would far sooner just bet with a site that is licensed (there are a few of them around now), and has syndicated games from Microgaming or Betsoft that have their games tested and accredited by independent labs. I don't see provably fair ever being anything more than a gimmick that appeals to a very small minority of players.