Even having a credit card reader isn't as convenient as knowing the price in advance before you get in and then having that price automatically charged, without having to do anything when you arrive except get out of the car.

London largely solved this by making it a violation of rules to have the car on the road with a broken card reader. Suddenly card readers got a whole lot more reliable. I haven't had an issue with a driver refusing to take a card since that started (but I have run into several with non-regulation card readers; clearly still trying to avoid paying taxes...)