After the backlash forced it into a humilating backdown, the supermarket giant's flip-flopping could become a future study for marketing professionals and public relations teams in how to avoid looking utterly pliable to the reactions of others.

It has come out looking weak, and held itself up to ridicule, after changing direction yet again following heat from environmental groups, and announcing an end date for its offer of free plastic bags.

The ACT has been there and done that on plastic bags. Long before the growing awakening to plastic's environmental harm brought on a widening rejection of plastic straws, the territory banned single use bags and made the sensible transition to the sturdier type. More recently, supermarkets in Canberra have discarded even these.

Tasmania in 2013 made the change from single-use bags without much fuss. South Australia long ago, in 2009, was the national leader in giving them a miss.

It was with the calm but slightly befuddled patience of a parent watching a child having a tantrum that these states and territories may have watched the reaction to Coles' cut-off date for free reusable bags.

The movement away from plastic is a gradual but sure evolution in public awareness, the kind that took place with smoking decades ago. It's not hard to see future generations asking an older version of ourselves today how we were so wasteful and thoughtless in using, and throwing away, plastic bags. Canberra long ago decided it wanted a better answer to these inevitable questions.

For their part, environmental groups can strike an overly earnest and patronising tone in the matter. The bizarre, ACT government-funded video discouraging plastic bag use that emerged this week showed that sometimes environmentalists don't help their cause.

With the changing social rules and attitudes about plastic, there's also the inconvenience that comes with breaking old habits. Some people have ban-fatigue and little patience for green sermonising. Others feel like they're being constantly told what not to do.

These misgivings are real, whatever their merits. In the case of shopping bags, the adjustment is also trivial. It takes one or two trips to the supermarket forgetting to bring them, paying 15c each to buy some, and most people will have soon adapted. If they still haven't, 15c isn't much to pay for most shoppers.

The environmental benefits are simply worth the initital, and temporary, inconvenience. It is estimated by 2050 there will be more plastic than fish by weight in the world’s oceans.

Shoppers need to be a bit more organised, but they're up to the task. Coles as much as denied this by caving in to those resisting the change. At some point, companies need to treat their customers like adults, and if they don't respond in kind, they'll eventually do so.

What was encouraging about Woolworths' and Coles' move away from single-use bags was they appeared to be taking some leadership and environmental responsibility. Unfortunately, this week, Coles wobbled under the pressure that can bring.