and eating potatoes everyday makes you fat too>I know there's a big difference in price,
you don't really have access to vegetables if you live in a USA city, between the time it takes to go to work and eat, your cheapest, least time consuming option is fast food
that's problem number one. problem number two is that you get raped with taxes and if you leave below the poverty line in the USA every dollar counts. electricity isn't cheap there.
In the end the "a dollar a burger" deal fast food pushes in the USA ends up being simply more cost efficient than what you spend with cooking and from taxes. You are talking a full, gringo sized meal with free coke refills if you spend another dollar. In Argentina, my country, 2 USD would be little below 60ARS which doesn't even let you buy a basic burger. The price difference is ridiculous.
It's a known fact that poverty and obesity go hand by hand. Countries like mine end up forcing people to eat pasta every day because a full day's worth of pasta is like 30ARS and you can cook it dirt cheap, specially considering out tax subsidies. Eating pasta everyday WILL make you fat. the less diverse your diet is, the worst it's for you. Other foods, like potatoes, have the same effect