On the documentation for reward tier levels they all usually say "invite only" or "if eligible" for the top tier.

You can walk up to a Total Rewards counter and get a Diamond card as soon as you hit the tier, but not for 7* according to the booklets.

MLife is the same with the top tier. Even if you have the points you have to be invited.

At all of the Caesars properties I've ever been to the full pay JoB 9/6 or Bonus 8/5 and similar games all have a special placard on them that states "This machine awards 1 tier credit for every $25 wagered" or something along those lines.

Not getting into proper plays etc, but I've counted over a hundred hands without a full house before on Bonus so the 7/5 paytable would not have bothered me...