I'm sure there was something in one Traveller publication -- I can't remember which -- that gave an example along the lines of someone replicating "authentic" Anglo-Terran cuisine, which was "kangaroo burgers and crumpets on the barbecue with mustard" or something like that, because they're not going to know that British, American and Australian were different things, any more than the average person dressed in "ancient Greek" cosplay knows which city-states were which.
I wouldn't be surprised if those authentic diners were dressed in something that blended Victorian England formal wear, 21st Century American casual attire, and, say, 22nd Century Australian Imperial uniforms (yes, the dread Australian Empire is coming). While somehow talking about how Ben Franklin, Ned Kelly, and Mr. Bean were possibly the same man.