With that amount of food for 4 people, I wouldn't expect leftovers, it's about the right amount.
But doesn't anyone talk to each other? You discuss what you want when ordering. When you're having the meal, you talk about how much you're enjoying the food, if you're getting full, whether you're planning to save some for lunch the next day etc and whether or not anyone wants anything saving or if it can go in the bin.
I always have a leftover lunch because any takeaway if you get curry, rice and a side, Chinese equivalent or a 12 inch pizza, that's two meals for me.
On the matter of rice, if it's not included in the price of the meal, which it usually is here, but if not, we don't buy it, because it's expensive for what you get. We keep microwave rice in and use that instead. Waitrose pilau rice is very good and only 70p.