No casino in the states of NV, CA or LA has ever informed me nor have I seen other patrons be duly made aware of the 2%-15% for the slots nor the 1% for Blackjack, Video poker or Craps.
In Nevada, I don't see any stipulation they're even required to, by the Nevada Gaming Commission. [1]
[1] LICENSING AND CONTROL OF GAMING - GENERAL PROVISIONS