(OOC)
I totally respect your idea however,
I think that this could potentially wipe out or be wiped out by the taxi service. The taxi services are already established, with commands and a structure of people working. Furthermore, they are also supported by the developers and administrators so their issues are instantly fixed. Furthermore, I don't see how you will make money off of this because for example, taxi drivers have their own salary that is given to them each hour along with the money they receive from passengers (which is pennies, really).
On the other hand,
I would support the idea of having your company go under the same name as the taxi company but under a different division? Or maybe have both uber and downtown cab co under the same /taxi command so that both factions have a chance to respond and whoever responds through a command first, gets to go to the call. This might be interesting to see.