How plastics have changed the world both socially and economically project?
Answers
Economically: As Xander mentioned, they are cheap and versatile. That means that more people can have more “stuff” for a lower net societal investment. I’m reminded of a few incidents in one of my favorite SciFi/alternate history series 1632: The Ring of Fire by Eric Flint. Basically, a modern American small town gets hurled into the middle of Germany during the 30 years war. It turns out that (among many other things) the “disposable” plastic water bottles were a hot commodity.
Socially: These changes and effects are largely a consequence of the economic impacts, and include lubricating social mobility for larger numbers of people. More “stuff” more efficiently produced and more readily available raises the standard of living for more folks. Being both widespread and “new” and having been introduced in a relatively short time period probably means the social hierarchial restrictions didn’t have time to come in to play.