At least 2500 businesses actively submitted, presented to the select committee or contacted Government during the consultative process to voice their concerns, the EMA says.
"The [90-day trial] was a critical one for our guys," McDonald said.
"Twenty or fewer workers is a very low threshold. We've been on the road and had employers of up to 400 people say we use it for everything."
"It's about giving people opportunities. It's very difficult to find people so they are taking chances on people that might not ordinarily."
The feedback from surveying members was that more than 90 per cent of workers taken on in 90-day trials were staying on, he said.
"It works. So we're asking what is the problem the Government is trying to fix."
A report by law firm Bell Gully highlighted several tweaks to the legislation that have been made by the select committee.
These included clarifying how an employer's obligation to provide information to new employees, and about the union's related role and function, would work in practice.
"As a result of consultation the Select Committee has made changes to the Bill that make it more effective," said Minister for Workplace Relations and Safety Iain Lees-Galloway. "This bill restores workers' rights, many of which were in place as recently as 2015. Employers will recognise this legislative structure and the economy thrived when they were previously in place."
But employers remain far from convinced.
The feeling was that this Government was looking back 10 years removing flexibility, rather than looking forward 10 years - as it had indicated it wanted to with the Grant Robertson led Future of Work group, McDonald said.
"You can see this setting up a kind of 'them and us' attitude and ending up quite antagonistic," he said. "We don't want that."
Unions were happier, applauding the Government for sticking to its original policy proposals.
"Government has held firm on their Cabinet commitments, despite cynical attacks by a big business lobby willing to splurge on advertising," said NZ Council of Trade Unions President Richard Wagstaff. "The Employment Relations Amendment Bill tackles many of the damaging actions taken by the previous National Government that made it harder for working people to get ahead."