Splitting up restaurant bills is annoying.

Good friends often avoid this cost by one of them paying for both one time and the other doing it next time, or better yet, by not keeping track of whose turn it is and it evening out in the long term.

It’s harder to do this with lesser friends and non-friends who one doesn’t anticipate many meals with because one expects to be exploited by a continual stream of free-riders who never offer to pay, or to have to always pay to show everyone that you are not one of those free-riders, or some other annoying equilibrium.

There is an easy way around this. Flip a coin. Whoever loses pays the whole bill.

Why don’t people do this?

Here are some possible reasons, partly inspired by conversations with friends:

 They don’t think of it

Coins have been around a long time.

It’s hard to have a coin that both people agree is random

One person flips and the other calls it?

They are risk averse

Meals are a relatively small cost that people pay extremely often. They should expect a pretty fair distribution in the long run. If the concern is having to pay for fifty people at once when your income is not huge, either restrict the practice to smaller groups or keep the option of opting out open.

Using a randomising method such as a coin displays distrust, which is rude, but not using one would be costly because you don’t actually trust people

A coin could also display your own intention to be fair. And it doesn’t seem like such a big signal of distrust – I would not be offended if someone offered this deal.

Buying meals for others is a friendly and meaningful gesture – being forced to do it upon losing a bet sullies that ideal somehow

Maybe – I don’t know how this would work

Asking makes you look weird

This is an all purpose reason for not doing anything differently. But sometimes people do change social norms – what was special about those times?

Sharing in the bill feels like contributing to something alongside others, which is a better feeling than paying all of it against your will, or than not contributing at all.

Maybe – I feel pretty indifferent about the whole emotional experience personally.

There are many inconvenient small payments that seem like they could be improved by paying a larger amount occasionally with some small probability. Yet I haven’t seen such a method put to use anywhere.