Mr Key agrees with retailers who say Easter trading laws are a shambles.
Paper Plus Wanaka store manager Chris Lumsden said he hoped Mr Key's calls would mean some action from Parliament to correct a "thoughtless" law change by MPs in 1990.
Previously, the law allowed for special-exemption applications from local authorities to allow retailers to trade during Easter, Mr Lumsden said.
The exemption allowed holiday towns such as Wanaka to cater for people arriving for large events, he said.
"No-one has been prepared to change that anomaly," Mr Lumsden said.
Court verdicts handed down to Wanaka retailers for trading in defiance of Easter trading in the past had more weight than the Prime Minister's call, Mr Lumsden said.
"We've been charged with breaking [Easter trading] laws, defended it, beaten it, and continue to trade," he said.
There have been 10 unsuccessful attempts to have Easter trading laws changed by Parliament in the past 20 years.
Rotorua MP Todd McClay's private member's Bill was the most recently defeated, going down by three votes last December.
Waitaki MP Jacqui Dean is readying another attempt to change the law - a local authority Bill which will only apply across the Queenstown Lakes district - after her own private member's Bill was defeated 87-34 in 2007.
Mr Key said MPs voted independently of their parties and along electorate lines when exercising a conscience vote to change Easter trading.
"My own personal view is that there should be relaxation of those laws," he told Newstalk ZB yesterday morning.
"I've always voted to liberalise trading on those appropriate days, and the reason for that is while I recognise some people would then be required to go out and work, there are a lot of people who actually want to go out and work on those days."
Base Wanaka ski, snowboard and streetwear shop owner Brent Harridge said Easter trading laws had never been consistently applied to retailers.
The judiciary had not punished Wanaka retailers who had traded in the past, he said.
His company had been convicted and discharged with no fines - "not even court costs" - the last time it was charged with breaching Easter trading laws.
He backed Mrs Dean's Queenstown Lakes Bill as the most likely attempt to be first to change Easter trading laws.
Wanaka Perendale Wool Shop worker Marilyn Fraser said she hoped Mr Key might help MPs change their minds about Easter trading.
Wanaka had been "bursting" at the seams over Easter and lots of people had visited the shop.
Holiday events such as Warbirds Over Wanaka brought lots of visitors, and some wanted a variety of things to do when they visited Wanaka.
"Not every woman wants to go to an airshow. A lot of them like to shop," she said.
Auckland's Newmarket Business Association is also lobbying to have the laws changed so confusion is eliminated.
Association chief executive Cameron Brewer said there was more confusion and frustration at the weekend than ever before around Easter trading laws.
"It can't go on any longer," he said.
Mr Brewer said "confusion reigned high" as Wanaka and Rotorua retailers were banned from trading while Queenstown and Taupo were not.
There was also confusion around licensed premises, cafes, gardening and hardware stores.
"Cafes can open if they have ready-to-eat food, but what is ready-to-eat food? More and more hardware stores, most of which have big gardening departments, are opening and facing $1000 fines, even though gardening shops can legally open on Easter Sunday."
The Department of Labour says the number of shops found trading illegally over the Easter break appeared to be similar to last year.
The department will consider the prosecution of 38 retailers after 19 were caught trading on Good Friday and another 19 on Easter Sunday.
A department spokesman said each case needed to be investigated further to consider whether exemptions could be applied.
The spokesman declined to specify whether Wanaka retailers were under consideration for prosecution
