And that seems to be the case with the decision of our largest supermarkets to ban single-use plastic bags at their checkouts.

The ban came into effect at Woolworths supermarkets on Wednesday and Coles is expected to follow suit at the end of the month.

Aldi supermarkets have never, to our knowledge, had single-use plastic bags meaning customers have either had to buy multi-use plastic bags at the checkout or bring their own canvas bags or boxes.

No doubt it’s a frustration for customers who forget to take bags with them, but over time we’ll all get better at remembering.

Few could argue that saving millions of flimsy plastic bags from finding their way into our waterways – where they have been blamed for choking sea creatures and birdlife – could be a bad thing.

And the supermarkets have made a point of highlighting just how environmentally responsible they are being in banning the bags, concerned as they are with protecting the environment.

For that, the sea turtles will be forever grateful.

But does anyone really believe this decision has been made with not even a cursory glance at the balance sheet?

Make no mistake, retail giants like Coles and Woolworths usually only make a massive change like this for one of two reasons – either because they were told to, or because it will make them money.

As it stands, though, NSW is the only state in Australia that has not yet banned plastic bags, yet still our supermarkets are falling over themselves to get on board with the ban.

So it must be worth their while to do so.

Plenty of cynics have made the point that the supermarkets will now able to sell bags to their customers to line their kitchen tidies or pick up after their dog – bags they previously got for nothing.

And not handing out an estimated three billion free plastic bags a year must also have a positive impact on supermarkets’ bottom lines. We wait to see if there’s a drop in grocery prices that reflects that improved trading position, but we’re not confident.

For all that, though, on balance we should welcome the plastic bag ban.

Whatever the reason for their decision, in the end it’s the right one – and that’s what really matters.