they can 'simply' (probably not that simple, of course), introduce higher fares for new users. never used uber myself, and if i did, I'd have little to compare the cost to. That 6% they need could easily be 7, 8, 9 or 10%, and I wouldn't know.

In my case, at least, living in NYC, I compare prices with what I pay for standard Yellow Cabs. Sometimes the Uber prices are not that much lower for routes that I know. In NYC, the Uber and Yellow Cab rates are almost the same. Compare that with Chicago which has far more reasonable rates. All of the inputs (car cost and operations, gas, labor of driver) is the same in NYC and Chicago, yet NYC is far, far more expensive for users. Gett and Via (the later is a carpooler) has much better rates.

For the rates Uber charges in NYC (UberX)

Base Fare: $2.55. (NYC Yellow Cab - $2.50) Per Minute: $0.35. (Yellow - $.50) Per Mile: $1.75. (Yellow - $2.50) Cancellation Fee: $5 (Yellow -- no cancellation) Service Fees: $0 Minimum Fare: $8. (Yellow - no minimum)

Chicago: (Uber X)

Base Fare: $1.70 Per Minute: $0.20 Per Mile: $0.95 Cancellation Fee: $5 Service Fees: $1.40 Minimum Fare: $4.40