Taxi accessibility varies wildly depending on where you are.

I lived in a small city (700k-ish people) for a decade and almost never saw a taxi on the streets. One morning, I locked my keys in the house and had to call a cab to take me to work. It took 30 minutes for a taxi to arrive. I lived literally one block away from the city's taxi depot.

A couple of years later, Uber hit the scene. With their service, I never waited more than 8 minutes for a ride anywhere in the city.