Blender seems to initially assume U=0.0-1.0, V=0.0-1.0 regardless of the image shape.
If I open Properties in the UV Editor, and mess with the aspect ratio values, the image texture can be distorted to a square, and then the unwrapped “square” vertices also appear as a square – not what I want.
Probably not worth all the trouble. Workaround is to only unwrap on a square image (make an edited image copy if needed).
It would be convenient sometimes to have a “project from view, preserve shape” option. Maybe it exists and I haven’t found it. Maybe my use cases are unusual (but I’ve run into them from time to time).
