The law is retrospective, cancelling 33 current claims affecting 150,000 female workers which now have to be restarted.
Workplace Minister Brooke van Velden last week said the changes would raise the threshold for proving that work had been historically undervalued, and would also save the Crown money.
Luxon told RNZ's Morning Report programme today that claimants had already waited years and they did not want to draw things out.
"We have moved quickly to make sure that we can actually get one system in place as quickly as possible and to give people clarity about going forward and to focus this act back on its core intention, which is to eliminate sex-based discrimination.
"But I've seen a lot of reporting over the weekend to say that we are getting rid of equal pay, we're getting rid of pay parity, we're getting rid of collective bargaining… that's wrong."
Luxon said they wanted one robust system and said "the opposition, the unions, and frankly the media have been actually scaremongering and a bit disingenuous" about what effect it would have.
There was no regulatory impact statement, no select committee nor public consultation done on the changes, which were passed into law the same day they were introduced.
The sections for reports and advice on the bill on the Parliament website are blank.
Questioned on what advice had been sought, the Luxon was vague.
"What we've done is we've just said, look, we want to make this clearer and clearer, less complex, less complicated, which Labour got completely out of whack."
Asked what evidence had been collected prior to the bill's introduction that it would work, Luxon said they "moved quickly so that people who have actually been waiting a long time to submit claims can do so without being stalled out".
Asked if he had advice from either the Ministry for Women or the Productivity Commission, Luxon would only say Cabinet had received "advice from a number of officials", but would not specify exactly who they were or what departments they represented.
Asked whether grandfathering in existing claims or running a select committee process were considered, Luxon again did not answer.
"Well, we chose this route, as I said, to make sure that we've got one system and to make sure that people aren't strung out unnecessarily. They've been waiting years to be able to submit claims. They can do that under the new laws. Yes, we are tightening up the comparators. Yes, we're tidying up to make sure we've got specific claims, not broad claims."
Labour and the Greens criticised the speed of the bill's passing into law, saying it was at odds with Cabinet's signing off of a proposal for ACT's Regulatory Standards Bill, which sets out new checks and balances for what constitutes good lawmaking.
