It is unfortunate that plastic is such a wonderful material to mould and build products out of. Waitrose sells shopping bags made from it, as do all the other supermarkets. It is widely used in packaging and shipping goods around. Huge volumes of plastic is generated by the recent development of online shopping and companies like Amazon that use vast amounts of plastic to bulk out products to fit a standardised range of (virgin) cardboard.
However, many alternatives are available for those 6-7 people in the UK that give a shit. The problem is that these alternatives are generally more expensive and so the additional packaging costs make the product more expensive. The end consumer can see it cheaper on the internet so buys from online sellers or eBay shops.
We re-use cardboard packaging as much as possible and re-use any plastic anti-damage packaging. I also collect boxes from local customers to re-use them and recycle the offcuts and damaged or unusable boxes. The main plastic waste we cannot do much with is shrink wrap on palletised goods. I generate so little waste my landlord lets me dump what we do throw away in his skip. If you watch what his business throws away you would wonder WTF is the point of my efforts. Some days I do.