"Richard Clark"
Practical cell sizes usually have a small radius
of around 5 miles or less.

www.google.com/search?q=Wi-max+miles
www.google.com/search?q=%2B802.16a+miles

Getting a lot of hits for "30" miles.

This doesn't contradict your quote, just expands upon it.

For a house in the woods with a suitable high gain antenna, the max range
could tend towards the extreme distances. For IP to cars, less.