The simple reason why they don’t do it: It has to be 100% reliable. Robots get stuck, need charge, software has bugs, … So your fleet of robots would need supervision. Probably for years to come.
And a human driver only costs like 70-80k a year.
Idk where people are getting the idea that systems designed to mimic biological brains will have machinelike precision whilst also being flexible to adapt to new situations.