Coming from Europe & Asia, the amount of crap fed in America is just crazy: like “is that for ONE person?” (more like an entire table of 4) since what is considered “normal” is just beyond what my stomach can handle, whenever I see their portion sizes: it makes me puke. (No wonder why they have a higher rate of obesity…)
Food being cheap != cheap food being the norm
No, but it is more a sign of what a restaurant or store will focus on. If the raw ingredients are of lower costs than rent and labor, it may make more sense to provide more food.
For restaurant culture in the USA, there is generally a focus on large portions, free tap water, few courses, and turning tables over quickly. A lot of early fast food chains were effectively food factories, skimping out in rent and reducing labor costs because those are the major costs.