Cars are useful for more than personal transport. The minivan angle is under-appreciated. I regularly do recycling runs which completely fill the car. And I'm taking some prints to a gallery tomorrow. It would be impossible to transport them on a bike, and it would need multiple trips with serious inconvenience and possible glass breakage by public transport. Even a regular shopping run would be a struggle on a bike.

I suppose these are all optional, or the community horse and cart service would be a realistic alternative. Which might be true. But while oil is a very stupid idea, that's not inherently a given for cars. There are non-trivial costs associated with moving some things very slowly, moving them without protection from the weather, or not being able to move them at all.