[toast76]

Anything that makes it more convenient for people to get from A to B in a _car_ will, of course, create more traffic. Convenience increases usage.

Uber/Lyft may make it unnecessary for some folks to own a car, but a reduction in car ownership does not mean a reduction in car usage.

[EduardoBautista]

One thing Uber/Lyft do for sure is reduce the need for parking spaces, which are at a premium in SF.

[mgbmtl]

Not having to worry about parking would therefore be an incentive to go somewhere by car (Uber/Lyft) instead of public transportation.

[randyrand]

Not necessarily. Making car-pooling easier can reduce the numbers of cars while also making it more convenient to get places by car.