Fun fact: the guy who portrayed the native guy in those ads, Iron Eyes Cody, was Sicilian.

Crying Indian is such an interesting nugget of history. Paid for by the plastics lobby who saw the writing on the wall of getting regulated for excessive trash. This same plastics lobby also coined the term "litter bug" and tried to get the world to forget that bottled drinks were sold in reusable bottles that would be deposited, washed, refilled and resealed. But also like you said, the standard procedure was to just toss your trash outside and not worry about it before this campaign, in part because nearly all packaging was biodegradable if not completely reusable until about a generation before this ad campaign (the Ford model T literally came with instructions to reuse the crate it shipped in to make the truck bed for example)