If a person chooses not to use the carpool method, what makes you think that person will use another transit system besides their own vehicle.
I have a 4X4 full size truck that eats the gas, but I have no intentions to change my transportation on someone else's schedule. It's my life and I'll live it on my own time, not someone else's. And I'm sure there are a lot of people who might think the same way (I could be wrong). Besides, I'm a terrible back seat driver.
Our state is not heavy in carpooling which is somewhat proof we are set in our ways.
The price of gas keeps going up, so I (like most other I'm sure) will scrape the pennies form other spending activities to keep my way of life from changing.
You don't ever see someone holding a cardboard sign saying, "need ride to downtown". Maybe that's the next new thing to come. "Will work for transportation to work". I'll start making signs right a way.

NOT!!!