Quantities and activity levels matter, and the Italians don’t look like the people of Walmart. The Italians also don’t have the same demographics we do.
I’m Italian and was raised on a diet with lots of bread and pasta. None of us are overweight. The way I see it, for some people carbs don’t affect them in any way. In others, they gain weight. People just need to figure out which type they are when they go about trying to lose weight. Everyone’s genetics and biology are different and are not affected by the same things in the same way. A one size fits all diet wouldn’t work on everyone.