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.

True. I mostly meant not personal vehicles, so jut buses, trams etc. I supposed emergency services will use those dedicated lanes. or maybe civilization is so advanced those will be served via flying only. Idk just since fiction thinking.