In most European cities, taxi companies are small, almost mom-and-pop entities with anywhere between one and say twenty taxis. In fact where I am living now I can call 4-5 different ones all in my vicinity. If there was an app that consolidated the booking process for those - awesome!
But why would there have to be a company that owns the market globally - from Karachi to Karlsruhe, from Amsterdam to New York, taking 20%, killing competition by it's pure überstrong market presence, brand and financial backing.
The same people that hate Comcast for oligolopolizing it's market (and hence using it's almost-monopoly powers for their benefit) yet somehow wish Uber would succeed and take over the market around the world. Why? Because it's a hip SF 'startup' (if you can still call an entity with $1,500,000,000 in funding a startup)?