The commission's draft report last month recommended that Sunday penalty rates for retail and hospitality workers be reduced to Saturday wages, but to keep the higher pay for essential services such as nursing.
Unions have vowed to fight the recommendations, and the Australian Council of Trade Unions has lodged its submission to the commission, claiming the "attack" on penalty rates would result in a two-tiered workplace system.
In the submission, the ACTU says cutting Sunday rates were the start of a slippery slope and more workers would be expected to work weekends with "little or no" acknowledgment of "personal sacrifice" of unsociable hours.
The commission's report proposes the option of allowing the commission to make temporary changes to the minimum wage in exceptional circumstances.
It recommends tweaking unfair dismissal laws, so employees can only receive compensation when there was no evidence of underperformance or misconduct.
The ACTU says calls to slow down minimum wage growth could increase inequality and drive down overall wages.
Secretary Dave Oliver said the inquiry was Mr Turnbull's chance to show he was not in the pocket of employers and wouldn't attack workers' conditions.
"If you wanted to write a list of what was needed to make Australia less prosperous, less fair, less progressive, then the Productivity Commissions recommendations are it," Mr Oliver said.
"The commission has ticked every box for unfairness."
