They are so strict about keeping roads clean here in USA, I'll give a real life example.
My younger brother (who was 16 years old at that time) was driving on a Freeway/Motorway, in the state of Virginia. While driving he just tossed out a small plastic bottle on the road side. Some other driver either saw my brother tossing out the bottle and reported it to the police, as they have a phone number on Freeways and local roads as well, to report the people to police, who throw anything out of a car, or the local police was around.
The police chased my brothers car WITHOUT any sirens, silently, till 2 miles or so. Then the Police started the siren, to pull him off the road. Told my brother to WALK BACK 2 miles, and pick up that bottle and bring it back and keep it in the Car, and toss it, when it in the garbage bin, when he gets home.
This is how USA, keeps its roads clean. By practically punishing people, like what my brother had to do, walk back 2 miles and come back to the car 2 miles ON FOOT.
A great lesson for us all in this, to keep the roads and the country we LIVE IN, whether USA, UK, Japan or Pakistan, CLEAN.