The examples shown aren't cities of the size of Paris. Paris would be described here as more of the 'hypertrophic city', reliant on public transit, where for the author "When your primary focus is on walking, there is very little need to invest in extensive public transit".

The whole of Europe is full of small towns like the ones used as examples. There has been a big shift in living in the 20th century away from these places as modern jobs have shifted to larger cities.

Your example is right. Perhaps I should have said 'less connected environments' rather than 'low density environments'. Paris is quite dense and connected by public transport. Atlanta less dense, but probably easier to drive around. The amount of people within a 1 hour commute of the centre of either will, however, be hugely higher than the examples shown.