Why is America made fun of for its huge food portions when you get such good value for your money?

As someone who is an international student in Australia and absolutely dreading the extremely expensive and small portions of food here, I wish I were in America and could get that many food and calories. Like bruh isn't it supposed to be a good thing that you get so much food? I mean if you didn't want it then just idk give it away to people or store it for later. Why complain?