Why would you buy a 32oz pop? It'd probably kill you if you sucked it all down at once (the acidity would expend your body's stored alkaline buffers faster than their replacement rate and drop your blood pH to dangerous levels). People don't do that. They buy it in a nice, insulated container as to have hydration readily available and cold for their long shift. They're mainly blue collar and outdoor workers or traveling sales- and repairmen. The elite is totally ignorant of such lifestyles because their jobs are easy, comfortable, and in arms' reach of a mini-fridge for their three hour shift.
They thus develop a bias, cognitively confirming that "only fat people" buy large drinks. If you surveyed Big Gulp buyers, I bet you'd find the data reflecting the demographics of middle-and-low-class America. States full of elitists like New York would accept such bias in legislation: "we responsible few must take care of the poor, fat slobs that don't know how to take care of themselves." On top of being ridiculous, that's not the government's reason for passing the legislation.
Sure they might say it's health, but it's really TAXES. That's right: it's just a hidden take hike. Instead of buying a huge drink, you must now buy multiple containers to maintain your lifestyle around the government's meddling. Multiple containers means multiple flat markups adding to more sales tax revenue. Multiple containers means multiple per-bottle environmental fees and more revenue for state governments. It's a small and meddlesome tax increase, but it's a tax increase.
It's fine to get into a 'big-Sally-shouldn't-get-her-dirty-fingers-in-my-food' argument, but it's pointless. I know most of you like government regulations and food policing and such policies are just the logical extension of what you already support. We need to make it a 'stealth tax hike' argument to repeal Big Sally's newest intervention.