I gotta be honest: I get tired of hearing the phrase that we need to "catch up" with other countries. Didn't our ancestors leave those countries so that we could do things our own way? Besides, from what I can see we're already ahead of most of those countries.

The countries that have banned plastic bags are China, Ireland, Uganda and South Africa. Catch up to them? No thanks.
It seems improbable that we'll be using plastic bags in 20 years. And it makes sense to stop. If I remember correctly, we use something like 20 million barrels of oil to produce the plastic bags we use in a year's time here in the U.S. And if even half these bags wind up in landfills (I'd say it's much more than that), this is a problem.
But if we're going to reduce/stop our usage of plastic bags, it has to be done senseably. The oil we use to make these bags in a year's time is about the equivalent of the total oil we use in a day, isn't it? So that's probably not that big a deal. And what are the alternatives? Paper? I believe that paper bags actually require more oil to manufacture than plastic. And if I remember correctly from my grocery store days, paper bags are 3 times as expensive as plastic. So those costs wind up getting passed on from the grocers to the consumers. Grocery prices are already high enough. A tax at this point seems quite dumb to me.