Yep, good point. I am myself a huge fan of livable oriented infrastructure (bike lanes, pedestrian paths, public transportation) but the hard truth is that roads were initially designed for carriages and later for cars. A though I recurrently have is how would a city designed from scratch by a civilization that uses only bikes and walking look like?

Why should you use only bikes and walking? Cars/trucks have a role to play, it's just not the most efficient to move the majority of the people from one point to another. Simple examples: ambulances, firefighters, police, cranes.