Its an interesting point. I am in the UK and to some extent am 'learning the differences'. I do travel to Vegas frequently and know a lot of casino staff there as many used to work in London. I will make a few points for you or others to comment on as you wish.

In London, it is illegal for dealers to accept tips. Any other staff may be tipped, in cash or chips, and as a rule, individual staff or groups of staff (like doormen together) keep those tips for themselves. Until more recently, it was not unknown, particularly with the more exclusive casinos, for someone to actually pay the casino to work on the door.

In Vegas, the only people who have ever told me they cannot accept a tip are pit bosses and non-dealing staff within the pits. On some occasions they have suggested i tip at 'the nearest table' on the basis that all gratuities are shared. Others suggest it is not necessary as 'the house' gets it and no one else ever sees any benefit.

Also, I had always understood that it was normal practice to tip in LV, particularly at the roulette tables during the course of play, but in more recent times it has seemed to me to be more the exception than the rule. Is this because the casinos feel they are paying a fair wage anyway (or making enough money!)

Interesting to compare with Europe. In Spain, it is pretty much the same as I have experienced in Vegas. However, in France, you are expected to tip after any winning spin, else you will be treated rudely until you tip again.