They stir up all the crap on the side of the road and put it in the street. Broken bottles trash, Screws, nails? Who knows what
Yup, I see this along the rural roads too. If there is gravel along the side and the grass grows to the edge of the gravel
(or even into the gravel) then a lot of debris, along with grass, ends up on the roadway.
When my daughter was younger
(and living at home) I would not let her out riding the motor scooters unless she had long pants, tie on shoes, long sleeves and a helmet
and I warned her about those patches from lawnmowers. Both she and my wife thought I was crazy until the one day when she slid down the road after hitting that stuff. No injury to her, a few scrapes on the scooter ... but I got told later
(by my wife) that I was RIGHT