In the pre-purge National Review, Dinesh D'Souza published Myth of the Racist Cabbie, [October 9, 1995] which argued that when taxi-drivers refused to pick up young black men in New York they were acting on a perfectly justifiable fear of death. [There's more on page 58 and 59 of Paved With Good Intentions.]
The dangers of being murdered are statistically easy to prove, because, as Steve Sailer put it recently, "attention must be paid to a dead body."
But there was a further claim in D'Souza's article: "[M]any groused that African-American passengers frequently leave no tip."
This, if true, is more likely to affect driver behavior than muggings, for complex economic reasons. But it's one of those things that's difficult to prove. It doesn't exactly show up in the FBI crime reports.
Recently, however, there's been a study by some economists that actually does seem to prove it: To Insure Prejudice: Racial Disparities in Taxicab Tipping, by Ian Ayres, Fredrick E. Vars, and Nasser Zakariya.
We collected data on over 1000 taxicab rides in New Haven, CT in 2001. After controlling for a host of other variables, we find two potential racial disparities in tipping: (1) African-American cab drivers were tipped approximately one-third less than white cab drivers; and (2) African-American passengers tipped approximately one-half the amount of white passengers (African-American passengers are 3.7 times more likely than white passengers to leave no tip). Many studies have documented seller discrimination against consumers, but this study tests and finds that consumers discriminate based on the seller's race. African-American passengers also participated in the racial discrimination. While African-American passengers generally tipped less, they also tipped black drivers approximately one-third less than they tipped white drivers.
This is a fascinating example of "stereotype accuracy," black-on-black racism, and unregulated human interaction.
Hat, er, tip, to Tyler Cowen at a Marginal Revolution, who pointed out that "the authors wish to ban tipping [NB: they call it mandatory tipping] to limit racism."
(The title of this post is from a Louis Jordan song.)