I suspect that Bing's photogrammetry pipeline/presentation involves converting everything into a heightmap, because overhangs in Bing Maps are vanishingly rare

I suspect that Bing's photogrammetry pipeline/presentation involves converting everything into a heightmap, because overhangs in Bing Maps are vanishingly rare and I've only ever seen them on prominent landmarks (Brooklyn Bridge, McCormick Place, etc.) which might be hand-placed exceptions. Even the trees have "skirts" which drop straight down to the ground. This is a major contrast to Google Maps, which uses a mesh capable of representing overhangs, including trees and most bridges. (Bridges which are fairly wide and close to the water still get turned into causeways.) The fidelity is pretty remarkable - it'll even make an attempt at rendering power poles and traffic lights. There is a mod for FS2020 which attempts to use Google Maps data in place of Bing, although I'm not sure if it's just imagery or the photogrammetry as well. I haven't tried it myself so I can't speak to how effective it is (and I suspect both MS and Google might have something to say about it in their ToS).