technically matatu's are mass transit privately owned minivan buses and not taxis, Nairobi as well as other Kenyan cities are well served by ride sharing services like Uber and Taxify which fill the taxi need. The "tatu" or three came about because they used to charge 3 cents when they started out way back before my time. There have been some changes in the sector to address some issues like safety but it's got a long way to go. Interesting innovations popped up around the space e.g. Google launched NFC transit payments, Bebapay https://en.wikipedia.org/wiki/BebaPay, in Nairobi a couple of years back but killed off the project (I was part of the local team when this took off)
