[jpollock]

As the population goes up, the variability is likely to go down. Single people are less of a blip in the numbers.

This means you can run with fewer free beds than in a low population area.

For example, if you have 3.8 beds/1000 people, that's 4 beds in a town of 1000 people.

A single additional person is 25% of the beds in the small town. A car crash? You won't be able to fit them in.

In a city of 50,000 people, that's 190 beds, and random events fit in the slack much more easily.

Also, since the baseline is larger, it's easier to scale. The minimum addition in the small town is a whole bed, or a 25% increase in costs.

In the city, it's also 1 bed, but that's ~0.5%.