What the tip gives the person leaving it

Four friends finish dinner in Doha and the bill arrives with a service charge already on it. The quiet negotiation starts anyway.

One leaves a note on the tray. Another glances at it and adds a little to his own share. Someone asks, lightly, what the others are leaving, as if there were a correct answer and nobody wanted to be caught beneath it.

Nobody at the table is thinking about the waiter's wages. Something else is going on.

The tip is a ritual, first. It is what our parents did, and walking out without doing it feels like leaving a door open behind you. It is also a small lever: for a moment, the person paying gets to judge how the evening went, and say so. And it is a stage. A generous note left in front of guests says something about the host that a printed price never could.

That is why customs like this outlast every argument against them. The arguments are about fairness to the staff, and many of them are right. The custom survives on what it gives the customer.

That is true of most customs worth arguing about. Whoever wants one changed has to start from what it gives the people who keep it. Leave the custom in place and the useful work is making it feel sure instead of anxious. Take it away, and the ritual, the lever and the stage all need somewhere else to go.

Otherwise people simply rebuild them on top of whatever replaced the old custom, the way that table in Doha did, one folded note at a time.