MAGA MAN
Let's go Brandon!
Pretty rare, and most landfills aren't near pastureland. Landfill operators also watch the wind and put up barriers where trucks are unloading. If a cow does eat a plastic bag, she usually passes it. You also have to remember that cattle is going to be slaughtered anyway.
Fires are the same problem whether plastic is in the landfill or not.
Most landfills are in rural areas, and rural areas have farms. Dairy cattle aren't there for meat. They never pass a plastic bag- it's a death sentence.
Since plastic has a high caloric value the fires are much more intense than damp paper.