>60MPH in San Francisco is going to get you some pretty bad fines most of the time
A friend of mine Ubers in SF, and tries to do runs to and from SFO for maximum money. He doesn't live in SF either, but commutes a long way every weekend to work there because the money is so good.
>(1) You're assuming all miles and hours are 'billable', while in reality you would be driving empty towards a pickup and waiting for the next pickup.
There's a pickup fee which offsets this, and in reality you can usually chain together rides.
Also, there's an additional bill per minute if you are in traffic.