Shops would be allowed to open two hours earlier on a Sunday under new laws set to go into state Parliament next month.
Consultation on the reforms has begun with Premier Peter Malinauskas describing the changes as "sensible".
Under the proposal, shops will be allowed to trade from 9am on Sunday as opposed to the current laws which only permit them to open at 11am.
The bill also would also allow metropolitan shops outside the Adelaide CBD to operate on Boxing Day.
"It's about getting the balance right. It's supported by business, it's supported by workers," the Premier said.
The reforms tighten how exemptions are issued to allow trade on public holidays. The former Liberal government used those powers to allow stores to open in the suburbs on public holidays during the last term, including on Easter Monday.
"We don't think a free-for-all in terms of the exemption regime that the former government sought to exploit is necessarily the right approach," Mr Malinauskas said.
The opposition is yet to consider the amendments put forward by the government.
"I do note that on recent public holidays, South Australian shoppers who have gone to the shops have been very disappointed to find out that under the new regime those shops have been closed," said opposition spokesperson John Gardner.
For the bill to pass parliament's Upper House, Labor needs the support of either the Greens, SA Best or the Liberals.
The union representing SA retail workers welcomed the proposal but say shop trading hours should not be at the expense of workers and local businesses to the interests of interstate and overseas supermarket giants.
"For us, this consultation is about protecting retail workers' right to be treated with respect, to have a fair roster and to have public holidays off," Shop Distributive and Allied Employees Association secretary Josh Peak said.
"Our shop trading hours are one of the reasons we have one of the most diverse and most competitive supermarket sectors in Australia and this must be safeguarded."
Drakes Supermarket director John-Paul Drake was supportive of an early start on Sundays.
"We have line-ups at 11am at every store every Sunday," he said.
"More money goes into the economy, we'd employ more people and they are going to get more hours — so it's a win-win for everyone."
He preferred the proposed rules to deregulating shopping hours, which he said would be a "free-for-all" and benefit the "duopoly in this state" the most.
