Comment by gwern

It's probably the most comprehensive in terms of personnel and man-hours; those other mapping efforts are highly automated, but the descriptions of these maps imply a lot of people on the ground making them so detailed, since for a lot of the map details I don't see how you could reasonably get them from looking at a satellite map or a few public records. (Or perhaps they simply mean most comprehensive as in up to that point in time, which is a legitimate amount of hyperbole such an endeavour.)