This from treehugger is interesting.
Litter as a concept was invented by drinking and sweet manufacturers in the 1950s and 60s, before then everything was reused.
In 1947 around 98% of beer sold was in reusable bottles and almost 100% of soft drinks, but now its less than 5%.
So presumably, back in the day, as well as higher costs and less efficient manufacturing, the producers had to pay for the reuse logistics system, but by going disposable, this cost becomes someone else's problem, the consumer or the state.
I'd never quite thought of it like that.