Do you generally have doggy-bags (leftovers carry-out) outside the US? The portions sizes are large for a few reasons: 1) pricing needs to stay high as rents are still high or the restaurant will fold (most do anyway). 2) people often take leftovers home
So you pay higher prices for more food, and a 2nd (or sometimes 3rd) meal at home.
I think the bigger issue is that due to sprawl and walk/bike-unfriendliness, people take their cars everywhere. As a part of COVID restrictions my family has started using bikes to things we would normally get in a car for - e.g. get takeout or library - but most people don't.