Most people are in and out of their homes/offices/driving for only short periods of time...while they may see the trails and not register while they were out...if one was to observe the trails that were left over 2-4 hours on a blue sky day...they would quickly realize something isn't right as the day turns into a silver sheened haze and the sun goes silver (yet there are still shadows despite the vibe of it being overcast outside). Ostriches with heads in sand....or frogs in a pan of water.