To be perfectly honest, cab service in some smaller places is horrendous. For example, do you meed to get to work by 9:00am tomorrow morning? You gotta call about 6:30-7:am. It might take them 15 minutes to pick you up or two hours and you cannot order in advance. There are no places to flag them down, so you always have to order one. Oddly enough, I've found these poor cabs mostly in places with no other public transportation. This sort of things plays games with a lifestyle. A trip to the GP can easily go from an hour-long short visit to taking up most of one's workday. In these places, I'd have welcomed the choice, even though I find it more risky than a cab.

That said, in places with good taxi service (where I*m at, for instance), there isn't a reason to switch.