The sunlit side of the earth is far too hot to inhabit in many places - the ‘Coldside’ is uninhabitable in just the opposite way. Life clings on in a narrow, sunlit ring - a kind of Goldilocks Zone
Lane markings are a fraction of the triangulation.
We ourselves identify and confirm other urban waymarks via captcha which feeds the nav data -- bridges, signs, hills, hydrants, chimneys, lights. There is mass live verification from android auto in vehicles. There are many yearly layers of street view images and scans.