> Self-driving cars still take up space on the road

This is a false argument. Think about this: a bus every 10 minutes is effectively 500-900 meters long! It easily "takes" as much space as 100+ cars. In other words, nothing would change from the traffic perspective if instead of 1 bus every 5 minutes, you had 100 individual cars.

The "people in the shape of a bus" argument makes sense only when you're talking about the performance in a very narrow case of transporting people in a steady, uninterrupted stream of buses. Or if you need to size your traffic bottlenecks.

Moreover, a bus route necessarily is unoptimal for at least some people on a bus. They are effectively "thicker" than other people because they take up more "effective space". But wait, there's more! Buses also necessarily move slower due to stops, so the "effective length" of a bus becomes even longer because cars will clear the road faster.

But wait, there's even more! A single bus needs about 3 drivers to be effective. So with the average daily busload of around 15 people, you have almost 20% of the bus taken by the drivers on average. This makes bus trips pretty expensive. Not quite to the level of Uber/Lyft, but surprisingly close.

And these problems are fundamental. That's why urbanists like NJB don't like to talk about that.