The roadway includes the shoulder and the right of way. The width of the right of way depends on local law. Billboards are permitted, meaning that someone has applied for a permit to place the billboard, has paid for the privilege, and has followed the specifications for placement, structure, size, etc. Garage sale signs are often removed when they are discovered.
That was a great video! I have stopped to move a turtle once in GA, turantulas and toads. Snakes usually move pretty fast. I did stop to see if a king snake on the side of the road was injured and it was dead.
I really thought the experiment was a good one. I am sick of seeing dead turtles on the side of the road. To be fair, they are sometimes very small and hard to see but it is still so sad. I don't think you should hurt the people in the cars but I do wish that people would slow down so they don't hit the turtles. I have never actually seen anyone swerve to hit a turtle, though, and figured that the ones that were hit were accidents.