When you are paying that much, you are paying for much more than food. The servers are experts in knowing when they should be there engaging in witty conversation and when they just need to disappear (only to suddenly reappear right when you need them).

And of course, they are very discrete. I read an example where a guy would take is various mistresses to a restaurant like that even though he also dined there with his wife because the servers just knew they weren't supposed to give anything away.