The Berejiklian government, though, did not have that excuse, given the widespread support for NSW to join all other states in banning the single-use bags, he said.

"I don't think it would be a big issue for either side of government....it's just a no-brainer," Mr Harris said. He believes about 80 per cent of the public seem in favour of the phase-out while only about one in 10 find it "challenging".

Harris Farm started offering paper bags as a trial to wean shoppers off plastic, but it didn't take long for their need to drop off - from 2.5 bags per customer to just 0.4 - as customers got used to bringing reusable bags or took away their purchases in boxes the firm provides. Some even reuse the boxes.

The lack of alternative types of plastics - such as polylactic acid-based ones derived from corn starch - meant even committed companies would struggle to avoid fossil-fuel sourced ones if they wanted to, Mr Harris said.

"Business needs help and that's where the government needs to step in," he said. "Sustainability is not meant to be easy."

Still, in Mr Harris's view more and more people are "drinking the environmental kool-aid", and companies ignore that trend at their peril.

"As somebody posted on our Facebook site recently, 'It's just about having a little bit of respect for future generations'."

Greens push

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Separately, the Greens plan to step up  pressure on the government by introducing a bill to phase out all single-use plastic in NSW by 2023 in the next session of parliament.

“The community is on the frontline of this war on waste but the NSW government has not backed them up," Justin Field, the Greens oceans spokesman, said. "The ‘bagflipping’ over plastic bags from Coles has shown that governments can’t outsource this problem to corporations."

The bill would aim to cut the amount of plastic waste entering the ocean by 90 per cent by the end of 2020, and include the requirement of all new washing machines sold in the state by 2023 to be fitted with lint filters capable of trappic any microfibres and micro plastics.

It would also ban the manufacture and sale of all petroleum-based single-use plastics by the end of 2023.

NSW Environment Minister, Gabrielle Upton, said on Friday the government would continue to rely on the major retailers to ban single-use bags.