They wear pumpkins shells on their heads.
The article (which contains the memorable line “Road safety officials said calabash-wearers would be prosecuted”) reveals that the gourd ruse is not working. Pumpkin-wearing passengers cause the motorcycle taxi drivers to have their bikes confiscated and generally make trouble for all parties concerned. So why do they persist? Are they afraid of being thought of as bumpkins? Pumpkinheads?
Ah, it's superstition! These passengers fear that any helmet provided by the taxi drivers could be used “to cast spells on their clients, making it easy for them to be robbed.”
If this sounds like magical thinking to you, try pushing the button for the 13th floor next time you get on an elevator. Can't do it, can you? Of course not. Nobody wants to be on the 13th floor. (Yes, yes, I know the 14th floor is really the 13th floor. Now go away... I can't get my pumpkin to fit right...)
Pumpkin helmet photo by Ben-Millett.