In the US, the state of public transit outside of a handful of (very expensive) cities is significantly slower and less reliable than taking a car. I would pin the reason for this on the shift of people outside of urban areas into suburban ones, and the lobbying power of the automotive industry to convince the government and citizens alike that cars were the right choice.
If public transit is the fastest option in the area, people do choose to take it! That's the case for me too in the past couple of cities I've lived in. But most cities have a long way to go before they get there.
Aside from just talking about this from a convenience angle, a message that might help explain the issues with car dependency is how much more it costs! People that are more hesitant about public services might be easier to convince with a cost-based argument. This is a great video explaining the actual cost of car ownership.
It'll be really hard to get coordinates exchange over here too. Does anyone know if people regularly post good finds to a non-reddit website already?