There’s a little technical detail about incentives that suggests that Uber might be making a mistake in their policy of paying minicab drivers by the hour. That mistake being not quite getting the difference between the income effect and the substitution effect as it affects pieceworkers (those two effects together being what gives us the Laffer Curve of course).

The point is mentioned here:

I’ve been chatting to local minicab drivers about Uber’s operation in Manchester. They don’t feel threatened, or tempted. Prices here start at £1.50, and wages are hard for even those VC types to undercut. Uber have allegedly been trying to do this with the bogus guarantee technique: drivers around here are apparently on £10.00 an hour, anything above that gets kicked back to Big Minicab. They don’t fancy the deal. Even in slack times, when they’re not being robbed of their reward moments, there’s always the hope that a fare to the airport will show up, and that’s part of what keeps you ferrying people around all day. It means you can (XXXX) toddle off home a bit early, which you can’t do if you’re on Uber’s clock.

Uber, Lyft, Hurnya and whatever don’t seem to realise that there’s such a thing as a minicab work culture, intensely local and adapted both to the people who work in it and their customers.

Re those incentives: the income effect is the idea that we have a mental model of how much we want to earn in a day (or week, whatever). If we achieve that then we’ll go home: or if taxes rise then we’ll work more hours to make that target, if taxes on incomes fall then we’ll work fewer hours. The other is the substitution effect where if taxes fall we’ll work more hours as work now becomes more valuable to us than leisure and vice versa when taxes rise.

In general, across the economy, neither applies to us all all the time and both apply to some of us at least some of the time. It’s the mixture of both, according to personal preference, that gives us that Laffer Curve.

However, detailed empirical studies have shown that pieceworkers (and taxi and minicab drivers are one of the groups that have been studied) tend to be more subject to that income effect. There’s a definite mental model of how much they want to earn in a day and they’ll keep going until it is earned then toddle off to do something more interesting. This is why you can never get a cab when it’s raining of course: higher demand for cab rides means they earn their target earlier in hte day and thus, amazingly, an increase in demand leads to a reduction in supply.

Uber has thought this through with their surge pricing: in bad weather they increase prices and thus earnings to overcome this effect. But offering drivers a flat rate per hour is precisely and exactly the opposite and almost certainly isn’t the correct response to that known propensity to the income effect.

This isn’t the most amazing observation about the world, obviously, but it’s an interesting little application of the microeconomics we know to be correct. Piece workers are more subject to the income effect than the substitution: thus hourly pay for them might not be quite as effective in attracting them as one might originally think.