They have a partially driverless service in one small city where conditions are mostly perfect and traffic is light. The problem is slogging threw millions and

They have a partially driverless service in one small city where conditions are mostly perfect and traffic is light. The problem is slogging threw millions and millions of corner cases in the real world. A trillion miles on the highway are quite pointless, a trillion miles in one Arizona city will also not get you there. You need millions of miles in all driving conditions and train the car to always figure out 100s of details. Look at the Tesla presentation where just recognizing a 'Stop' is incredibly difficult. Working threw all these problems requires having 10000s of cars with real sensors sourcing data from you. The advantage Tesla has is that they can do this with zero capital, while Waymo needs to have a expensive cars (100 to 1000s) with a payed driver, go threw every location and create a HD maps.