Interesting question.
There's an argument for not paying people to represent their country in a sport, beyond expenses and compensation for injury.
If you agree that it's OK to pay people to represent their country in a sport, then it's hard to come up with a reason why anybody should be paid more than anybody else. It comes down to what are they being paid for[i?
One way to look at it would be to forget gender differences and start with a single team E.g. in the men's soccer team, are some players paid more than others? If so, then it's easy to see how that principle could be extended to paying other teams less. But if not, then I would say there's no argument that all players should be paid the same, no matter whether they're male or female.
The next complication comes across sports. E.g. should US soccer players be paid more than US skiers for representing their country?
And then add in disabled, veteran and, coming soon, transgender categories and it gets [i]really] complicated.
So much easier not to pay anyone anything for the honour of representing their country ...