Kangaroos and Jillaroos players are set to receive $40,000 each for the 2026 tournament, while players from other nations get $850 per match.
That means a player from another nation could earn $4,250 by reaching the final, compared with $8,000 per match for Australian players.
After Samoa's 44-12 semi-final defeat to Australia, forward Spencer Leniu criticised the disparity in a social media post on Monday.
"Let's be honest, the little nations carried this World Cup, yet we are paid 850 (dollars) a game to the Aussies 30/40k for the tournament," Leniu wrote.
He argued that Samoa and Tonga supporters helped draw crowds and build tournament atmosphere, saying: "They make it a triple header because the people turn up in numbers, fill the stadiums and create an atmosphere filled with pride and passion."
Leniu said Polynesian and New Zealand players would continue representing their nations, but their commitment should not justify overlooking their contribution.
He also pointed to the next World Cup being held in Utah and Hawaii, which have large Polynesian communities, and called for smaller nations to be compensated fairly.
"I'll use my voice and platform to push for change, because the next gen deserve it, if that means putting my head on the chopping block, then so be it."
Samoa teammate Jarome Luai reposted Leniu's message and tagged the NRL and Peter V'landys.