Public transport can do maybe 80% or 90% of the transportation needed, but obviously it can’t replace an Ambulance or the needs for a craftsman to have his tools with him. And it can’t do door to door transportation either.
There are limits to the flexibility and efficiency of public transport.
But in European cities with good public transport, most people don’t need a car. And when I lived in Copenhagen, there was a point where none of my friends had cars.