That's what Uber has done in cities all over the United States and Europe, and it's created quite a storm among politicians and licensed taxi drivers, who have held up traffic in, among other places, Boston, London, and Paris just to stamp their feet at the high-tech competition.
What is Uber? It's an innovator, and you know what means. It disturbs the regulatory landscape where protected firms have long settled in safely and comfortably. Suddenly, the advantage of being an "in" flies out the window. No wonder the regulation-spawned monopolies are upset.
To be more specific, Uber (and its competitor, Lyft) is a company whose smartphone app efficiently matches riders and drivers. When Uber enters a market, it carefully recruits and certifies local drivers. Then, using the app, people who need a ride can quickly find drivers to get them where they want to go. Customers are told fares in advance and how long they'll wait to be picked up. After the trip, driver and rider are asked to evaluate each other.