“Giving people more viable alternatives to driving means more people will choose not to drive, so there will be fewer cars on the road, reducing traffic for drivers.”
Concise, easy to understand, and accurate. I have used it at least a dozen times and it is remarkable how well it works.
Also—
“A bus is about twice as long as a car so it only needs to have four to six passengers on board to be more efficient than two cars.”
Your argument doesn’t work to make anyone stop driving cars, though. It just makes them pro non-car in the sense of freeing up traffic so they can drive their car quicker. It doesn’t make themselves take anything besides their car.
You don’t need to convince anyone. People will convince themselves if they are given the appropriate environment. This is about convincing them to support the construction of that environment.
Think about New York. It’s subject to the same cultural influences as the rest of the US but public transportation use remains high because the infrastructure is good and competitive with driving.
Honestly, if this gets people to advocate for me effective public transit so I can take it, I am fine with that.
People are stupid and biased towards the current state of things. Even if they support you now so they can drive their car better, if there’s a good bus route or whatever in five years they’ll probably use it.