The population center needs to service everyone who is in the wider area.
My example with Eau Claire and Eau Claire county - yes, the majority of people live in the city... and it is the largest area of population within an hour's drive.
Now, if you look at Assen, Assen itself is a suburb of Groningen which is only half an hour away and has 200,000 people.
The number of people who need to go into Assen because its the place to go for a particular thing is rather small compared to those who would go to Groningen.
Meanwhile, Eau Claire is the only level II trauma center for a very large area ( https://dhsgis.wi.gov/dhs/traumacare/ ).
It is necessary to build the city to be able to support the surrounding area - even if those people don't live there.
Meanwhile, another comment mentioned the city of Davis in California... which is a suburb of Sacramento. Or Portland Oregon which is surrounded by smaller cities (Beaverton, OR which abuts Portland has a population of 1.5x Eau Claire). In this way, the city of Portland doesn't need to support the surrounding area as much because the surrounding cities themselves area able to take that load on and so there's a much larger portion of local transportation rather than regional transportation.
If you were to draw that Voronoi chart for the Sacramento area, or Portland area, or Drenthe, NL you would find that the cities that are best able to support local bike commuting and build the infrastructure for it are not as dependent on the rural in the area between them and the next city of 40,000. It is quite possible that for Portland, that Voronoi chart would be entirely within the city proper.
> There's no reason folks coming from outside the city can't park at a periphery (or even central) parking structure and then bus/walk/bike to their destination, if we take the original corollary that Eau Claire gets perfect bike infrastructure tomorrow.
My parents live half an hour outside of the city that they're closest to. They go in to town once a week and get groceries to feed a family of five for the week. This fills up the entirety of the back of a SUV.
Doing a "drive in and park on the outside" wouldn't work for grocery or hardware or any of the other shopping excursions needed. I would contend that that is the norm for people heading into town from outside.
I live in town and can walk a few blocks to a grocery store with a small pack and get what I need for right now whereas my parents have to commit an hour just to commute into town and back out for groceries... and that's done to reduce gas use.
The point that I'm trying to make with this is that if you live in an area where the distance between cities of reasonable size is an hour or so apart, the city has things that pressure it into being built for regional rather than local travel.
One of the things to consider is in the days of old where regional travel was less common, the even smaller towns and cities were self sufficient rather than having people living there need to head into town.
When I was growing up, instead of heading into the city (30 min each way) for groceries or hardware, we'd go to the nearby town (10 min by car - possibly bikable in fair weather) that had a grocery store and hardware store. About 20 years ago, the grocery store closed and 15 years ago the hardware store closed (and last year, the pharmacy closed).
I believe that the path to encourage bikes and smaller transportation areas, the smaller outlying towns need to become more self sufficient in supporting the needs of the surrounding areas so that people don't need to drive half an hour or more to get to the grocery store or hardware store. By doing that, the larger cities serve a smaller area and in turn can have their infrastructure more focused on local transportation (e.g. busses and bikes).