What is the effect of tipping on the take-home pay of Uber drivers? Economic theory offers a clear answer. Tipping has no effect on take home pay. The supply of Uber driver-hours is very elastic. Drivers can easily work more hours when the payment per ride increases and since every person with a decent car is a potential Uber driver it’s also easy for the number of drivers to expand when payments increase. As a good approximation, we can think of the supply of driver-hours as being perfectly elastic at a fixed market wage. What this means is that take home pay must stay constant even when tipping increases.

But how is the equilibrium maintained? One possibility is that as riders tip more, Uber can reduce fares so that the net hourly wage remains constant. Since take home pay doesn’t change we will have just as many drivers as before tipping. Under the tipping equilibrium the only change will be that instead of the riders paying Uber and then Uber paying the drivers, the riders will also pay something to the drivers directly and Uber will pay the drivers a little bit less. The drivers end up with the same take home pay.

But suppose that Uber doesn’t want to reduce fares or is somehow constrained from doing so. Does the model break down? Sorry, but the laws and supply and demand cannot be so easily ignored. If Uber holds fares constant, the higher net wage (tips plus fares) will attract more drivers but as the number of drivers increases their probability of finding a rider will fall. The drivers will earn more when driving but spend less time driving and more time idling. In other words, tipping will increase the “driving wage,” but reduce paid driving-time until the net hourly wage is pushed back down to the market wage.

At this point many readers will object that I am a horrible person and this is all theory using unrealistic “Econ 101” assumptions of perfectly competitive markets, rationality, full information etc etc. To which my response is that the first claim is plausible but irrelevant while the second is false. A new paper, Labor Market Equilibration: Evidence from Uber, from John Horton at NYU-Stern and Jonathan Hall and Daniel Knoepfle, two economists at Uber, looks at what happens when Uber increases base fares:

We find that when Uber raises the base fare

in a city, the driver hourly earnings rate rises immediately, but then begins

to decline shortly thereafter. After about 8 weeks, there is no detectable

difference in the average hourly earnings rate compared to before the fare

increase. With a higher fare, drivers earn more when driving passengers, and

so how do drivers make the same amount per hour? The main reason is that

driver utilization falls; drivers spend a smaller fraction of their working hours

on trips with paying passengers when fares are higher.

My conclusion is that increases in Uber fares are a very bad idea. Why? Increases in Uber fares–i.e. increases beyond those required to have enough drivers so that pick-up times are reasonably short–have two negative effects. First, and most obviously, higher fares increase the price to riders. Second, higher fares don’t result in higher driver earnings but do result in drivers wasting time.

The situation is very similar to the inefficient market for realtors. When realtors earn a fixed percentage of a home’s sales price, higher home prices encourage more entry into the realtor market. But we don’t need more realtors just because home prices have increased! When home prices are high, a realtor can earn enough selling a handful of homes a year to make it worthwhile to stay in the industry even though most of the realtor’s time is spent unproductively finding customers rather than actually helping customers to buy and sell homes. It would be better if commission rates fell when home prices rose but even after many years of online entry that typically doesn’t happen which is the mystery of realtor rent-seeking.

Uber is a great service for riders and it’s also great for people who need a source of flexible earnings. The fact that Uber drivers earn less than some people think is appropriate is a function of the wider job market and not of Uber policy. Indeed, Uber can’t increase take-home pay by raising fares and if we require them to do so we will simply hurt consumers and waste resources without improving the welfare of drivers.