Its not - filter out the people who order the lobster and insist that they should pay less because their caviar was a smaller portion than your salad. Dine with people you like and respect and take it in turns to pick up the bill.

Also if you are the person that gets the caviar, lobster and 2 cocktails and the other person gets a salad and tapwater - you are paying.

Because nobody makes money from it.

I recall in university that many of these existed but all died as soon as they wanted payment. This seems like airline seat space. People find small seats painful. They find paying anything extra even more painful.