Nebraska

Well sometimes there's a single cab at the airport so I think we can narrow this down.

It can't be Omaha, because the airport is in the Iowa part of Omaha. And that area is hilly and forested once you get out of town. Though this could be Sarpy county between Bellevue and Papillon. Which would place this encounter at around 42nd and Cornhusker, and there are better ways to get there rather than driving over the fields so that ain't it.

It's not West O, because that airport explosively serves wealthy people and cabs just aren't there.

The terrain is hilly, but also cultivated with grain, but the fields are light green, just starting to grow. A red sky indicates impending thunderstorm. There are no trees so the farthest east side of my state is out.

So this has to be Lancaster county, the only other major airport that might have a single cab is in Lincoln, and the cab is to go to Omaha. Specifically, this is west of Lincoln, in the early spring. Which means not only does the mugger have a gun, so does the victim. Spider Man is also armed. There are 4 rifles and some deer meat in the trunk of the cab.