Drivers caused traffic jams all across Europe to protest Uber. (Twitter/@paulfabretti)

The drivers’ main concern is that the service is taking business away from them with drivers who are not required to have a license, while they have each spent over 100,000 euros ($185,400) on licenses and undergone many years of training.

Taxi drivers in London drove much slower than usual around the popular area of Trafalgar Square, causing traffic jams.

READ MORE: Uber Attracts Drivers From All Walks Of Life

Drivers in Paris blocked major airports of Charles De Gaulle and Orly and would not let private taxi services pick up passengers, while in Madrid, drivers blocked Paseo de la Castellana, a major thoroughfare, according to Bloomberg.

In Berlin, hundreds of drivers protested outside the Olympic stadium and drivers in Milan hung a banner reading “Illegality Reigns Sovereign!”

Uber CEO Travis Kalanick responded by saying that, “It's really common when we really succeed in a city that the incumbents -- the taxi industry -- are often trying to protect a monopoly that's been granted to them by local officials. They're trying to slow down competition.”

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