Pop in a bag

As I was discussing my trip with my family, I talked about "pop in a bag". Here it is. They take the soda from glass bottles, put ice in a plastic bag, pour the pop over the ice, stick a straw in it and keep the glass bottle for themselves to recycle. I'm not sure if they get money for recycling, or if they just reuse the bottle. Anyway, I think it is weird, but all the locals are drinking out of these bags.