I did solid waste dump responses when I worked for a health department.

When people who can't pay to dump have trash, they dump it in the woods, ravines, forestry roads, etc.

Usually the drive to dump trash is when someone dies and someone else is having to clear out their effects, be it family, a landlord, or some worker. Or someone is evicted from their home, vehicle, or encampment.

Otherwise most people hoard it until they die or are evicted.