The Monterey Bay Aquarium is a research and conservation institution as much as a visitor attraction, and its page on reducing plastic pollution is the one to send to someone who wants the basics without a campaign attached.
What it says
The advice is plain: carry a reusable cup and bag, store food in glass or metal rather than plastic, recycle properly, and support policy that reduces plastic at source. It notes that only about five percent of plastic in the United States is actually recycled, which is the number that moves most people from "I recycle" to "I refuse".
Why it is here
Most of the aquarium's advice is about habits a diner carries into a restaurant, and the page in this section on ordering takeout turns those habits into a checklist for the moment you order. If you want one link to send a friend who asks why any of this matters, this is a good one.