That's not a global thing. In the US, they use high fructose corn syrup a lot due to artificially high sugar prices (caused by US agricultural subsidies). Here in Australia, most processed foods contain real sugar (not high fructose corn syrup) since sugar in Australia is cheap (massive export-oriented sugar cane industry and a much more laissez-faire agricultural policy).

Obesity rates in Australia are a bit better than the US, but still pretty bad – US is around 40% of adults, Australia is around 25% – sugar vs corn syrup may be a factor, but I'm sure it is a lot more complicated than just that.