I think pixel is right on the mark. My wife and I visited family In Europe last year, plastic is just starting to appear. It's sad, something about glass just makes the soda better, and the sugar doesn't hurt.
Maybe the US bottlers will start producing, the coke products are all imported. That has to figure into the cost.
I seem to remember hearing somewhere that imported raw sugar is tariffed, but products made with that sugar then imported are not. I think that holds even under the
North American Free Trade Agreement, but don't quote me on that.
That would help explain Mexican sodas made with sugar being imported here, particularly where NAFTA is concerned. It may be cheaper to import them that to make them here. Especially if Coca-Cola US has not formally sanctioned this importation.
You can of course still get domestic Coke in glass bottles, but it's still sweetened with HFCS, and not much different from Mexican Coke in price. I have become concerned about the quality of the water used in Mexican Coke, however.