Which party is responsible for littering?

Someone sticks a flier on your car. You don’t notice until it flies off on the road or freeway. Who is responsible for littering?

Someone drives by and throws a flier towards your property. Are you responsible for picking it up? Does it matter where the flier actually lands? (street, sidewalk, median, etc)

Dump/recycling truck drops some stuff out of your bin(s). Does it matter how far it drops? (in front of your property, down the street)