According to [this resarch](http://www.schallerconsult.com/taxi/taxifb.pdf), 57% of the fare (including tip) goes to the driver, 24% to vehicle and gas, 15% to the owner, and 4% to other expenses.
So, the driver is a pretty substantial portion of that. Taking the driver out of the equation would substantially reduce the costs. If you increased medallion availability as well, and the owners were able to work with lower margins (or they were cooperatively owned), you could get the cost down even further, to maybe 1/3 of what taxis currently cost. That would be a huge difference in affordability for everyday use.
So, the driver is a pretty substantial portion of that. Taking the driver out of the equation would substantially reduce the costs. If you increased medallion availability as well, and the owners were able to work with lower margins (or they were cooperatively owned), you could get the cost down even further, to maybe 1/3 of what taxis currently cost. That would be a huge difference in affordability for everyday use.