Instead of hailing or calling a cab, waiting for it to arrive and making sure you have enough cash in your wallet to paythefare, Uber carved out a unique niche by greatly simplifying the entire experience.
When my sister asked her why she was just standing there, she said she did not have enough to paythe bus fare - the last time she used public transport, she had paid 1.5m Zimbabwean dollars.
Probably the most useful feature is the ability for a passenger to swipe their credit card on the machine to pay for thefare: that's right, no more fumbling in your pocket for change.