Plastic particles are now becoming as common and widespread as bacteria. If they really want to push the message on this then they would outlaw use of plastics in consumer packaging and thereby emphasize use of cardboard and paperboard products. The wood fibers used to make paper and cardboard are not harmful to animals, biodegrade quickly, and are far more environmentally renewable.
Plastics use less resources to produce, but pose a problem in that they will always stay plastic. Paper, cotton, etc use too much water and are often combined with plastic anyway to make them more durable, hygenic and increase shelf life of the packaging.
There's one issue with reusable grocery bags no one seems to want to mention. You have to wash them! More water, detergent or worse spray them with potentially carcinogenic anti-bacterials.