...and the ground is very unstable in many areas, not to mention under water.
Another benefit of flying is straight line transport. Roads -- particularly around here --- add huge distances to any trip because you can't go directly to one's destination, but instead, must go waaaaaay around to get there.
The best solution is actually monorails. There is no need for them to take up much ground other than a post every so often, they don't disturb the greenery or the wildlife or the settlements, they can mostly ignore terrain, they can go whiz-bang fast, they can never hit cows or cars or people (well, REALLY stupid people they might hit, but I see that as a feature, not a bug), properly built monorails can't be snowed in or under, the scenery is better than either aircraft (too high) or car/train/bus (too low) they're quieter than trains by far, the ride is better, elevation means better radio coverage for cell or whatever, two tracks for bidirectional operations can be hung from single poles, thereby taking no extra right of way.
Also, they're hella cool.
Too bad the government hasn't enough sense to Manhattan project a bunch of 'em. Sure rather pay for that than yet another bombing of brownish people with funny beliefs and (coincidence only, of course) oil and other natural resources.