Try walking into a club in the Western world where you're not a member and see how many drinks you get served at their bar. Same concept, really. And if being introduced by a current "member" is all it takes to get served, that's a pretty low entrance fee. I am a regular at a number of such establishments in Japan, and it doesn't matter what color or nationality you are. They just want to make sure you're somebody they know is willing to serve as a reference for you.

The fact that they are restaurants and are, at least physically, "open" to people walking in from the street, doesn't mean that it's "open" to anybody to just doing so. This is a disconnect with Western mores, where a private club or restaurant would be not as "obvious" from the outside, and would signal its "privateness" more directly.

Here's an example for you, of Annabel's in London: https://membership.annabels.co.uk/ Youse gets your "letter of support" from a member, you're welcome to join. Otherwise, sod off.