I haven't personally owned restaurants in both SG and USA, but what I understand is it is way easier in SG in terms of red tape, capital, insurance etc. I think that's a very valid criticism.
The food in America is diabolical. The amount of processed food with too much salt, sugar and fat makes you ill after a while.
For the difference in health outcomes I’d start to look here. Especially as poor people have very little healthy options in the states.