What will mobile kill? Part 4: Cab Companies

Cab companies serve two purposes: (1) to connect customers to certified people who have cars nearby and can pick them up; and (2) a measure of quality control (such as it is) over the drivers and cars. Both of these are put at risk by mobile devices.

It won't be long until I can ask my phone: "Where is the nearest cab?" and then use it to send a text message with my current address and ask to be picked up. Why do I need an intermediary? Further, I'll be able to rate my experience with that cab and driver so that the next person who wants to use them can see if the car smelled bad, the driver swerved too much or was listening to something obnoxious on the radio.

Cabs won't go away, but the intermediaries will be hit hard. By the way, why hasn't someone done this yet? Those of us who live in a city where cabs don't just drive by us every minute could really use something like this.