Right, but having to use your second car for that trip and only that trip is probably a rare occasion for many families. I imagine the most common cases are two

Right, but having to use your second car for that trip and only that trip is probably a rare occasion for many families. I imagine the most common cases are two cars that are both used regularly because both parents drive to work, or one primary car that can be used both during the week and for that Saturday morning trip, and the second only for the rare occasion that the primary car is broken or being used for something else. My point is not that nobody needs a second car, my point is that focusing on rarely-used cars is by definition not a major societal issue. What you're describing is a very real issue, and might be more appropriately addressed by improving public transit. Uber's idea of replacing your second car with ridesharing does not work, as you say. Edit: Also note "most of them are in two-person households." So it seems they're mostly focused on couples without kids.