This is not an issue I have ever experienced. I can’t get reliable coverage in my office but planes on the ground seem to be fine (mostly Denver, Detroit, Minneapolis, Des Moines). Maybe it affect some airports more than others.
Perhaps it's only certain service providers, airports, or just airports the author has used and is extrapolating?
The 700-850 MHz band had some good range (miles), so while there might be challenges from being in a metal tube, is be somewhat surprised if there's not a mobile tower nearby.. if not multiple. The usual problem in this setting is overcrowding, so most highly populated public places have overlapping coverage. The author makes it seem like no cell towers would exist within 10 miles of an airport, which would mean nobody near an airport would have good service (including homes, or roadways)
One of the first projects I was given as a junior engineer was to measure signal strengths of our and competitor mobile networks at the local airport. This was pre September 11, but I was still amazed at the access we got carrying a signal analyser and just flashing our employee badges got us.
For inbound roaming users, absent particular partner network preferences (which were less common back then), the mobile device would select the local network to use based on relative signal strengths when turned on. Capturing those inbound roaming fees was a high priority for the product managers and hence a lot of effort and infrastructure investment went into this.