This is a web page sponsored by the American Chemistry Council, who I presume represents plastic bag manufacturers. I'm not going to say to much about what they say except that they are obviously promoting the benefits of plastic bags. You can read what they say and draw your own conclusions.
In all your discussions on the web page "what you should know about plastic bags', you never mention reusable bags. You only compare plastic bags to paper bags. I will say to you, based on personal experience, our plastic bag consumption has been reduced significantly by not using plastic shopping bags, but rather by using reusable bags. I think you are misrepresenting what is actually occurring in the consumer market.
In addition to this, many of the stores in our area now ask "do you need a bag'. This is not only at grocery stores, but in many retail stores. At one time, convenience stores would even put a newspaper in a bag, even if that's all you purchased. Seemed quite silly to me. Now, that doesn't seem to happen. In fact, I almost have to ask for a bag if I have a bigger purchase that I can't carry in my bare hands.
My take on what is influencing this trend is twofold. One, retailers are becoming more aware and more corporately 'green' because of consumer patterns. Two, retailers are finding that their operating costs are reduced if they don't hand out bags for every purchase.