Because they are...

Have you ever had to haggle about the cost of your trip with a taxi driver?

Have you ever ordered a taxi and one never showed up?

Have you ever missed your flight, because a taxi - that was scheduled to pick you up at 5AM just didn't arrive?

I used to do consulting work all over Europe and literally spent 5 years of my life flying every single week. Pre-Uber taxis were horrible! In fact, they still are!