For those people who see this argument as inapplicable, you're right for many people today. Sam worries about UberX rates going up. The exact opposite will happen. They have steadily pushed prices down since inception. They've also started realigning the price more towards time and away from mileage and have much farther to go.

UberX will eventually charge prices more like $0.60 per minute plus $0.20 per mile.

A rough estimate based on the distribution of miles driven is that 30% of Americans should give up their cars under these numbers. Of course, many won't because owning a car isn't purely a financial decision and humans change slowly.

Discussions and imagination move much faster than reality but the world will catch up.

Technical note: The price per hour should be (time-related depreciation)/miles + hourly wage divided by the utilization rate. Mileage should be the sum of fuel costs per mile, maintenance cost per mile, and mileage based depreciation.

Running these numbers for a driver expecting $20 per hour (Average for a Taxi driver is ~$12) with 2/3 utilization and driving a Prius yields a pricing structure of ~$0.60 per minute and ~$0.20 per mile.