I'd venture an educated guess that shipping in glass is cost prohibitive compared to plastic because of the weight difference between the two types of containers. Add the recycling costs of glass and the resources required (water, heat, etc..) and it's probably even more costly.
I think the article's conclusion is exactly right that we need to stop shipping plastic all over the place and simply incinerate it, reduce the bulk by 80% or more and make it more safe to dispose of vs. what's currently being done.