At the same time, when I go out for dinner at home, the best restaurant experiences are always when I feel 'almost full' when my plate is completely empty, and still have some room left for dessert. Nothing needs to go to waste, and I don't need to take doggy-bags home so I can eat more of the same bland (and now re-heated, soggy) food the next day, as is common in the US (doggy bags are an extremely rare sight where I live). The 'dining out' experience could hardly be any more different comparing the US to the restaurants at home. To make things worse, prices are also way higher in the US, at least the more urban areas in the east and west.
I remember one time staying in an AirBNB in the US, talking to the host who used to own a classic american diner. She had the exact same thoughts about food quality and portion sizes as we did, and told us she actually tried to do it different in her diner. Customers would by default get a small plate of food, but could order more for free if it wasn't enough. For some bizarre reason her customers hated it and kept complaining about the portion size. So she switched back, and almost no-one ever finished their food completely again.
Very quaint obsession with quantity, if you ask me.