Here are the points anti-feminists make:
1) Women choose lower paying jobs
This is true. But kinda bullshitty, isn't it? Is it just a coincidence that women aren't as likely to choose lucrative careers, or is there a teensy possibility that they're being systematically drive away from those jobs? Is it a coincidence that we as a society don't award careers with lots of women the same as the careers full of men? Are nurses and teachers not in demand or important? You could shrug and say "yup, it's a coincidence! must be biology, estrogen just cancels out our need for money!" and stop the conversation right there. Or you could ask some more questions. That's what feminism is... we hold up signs to say "there's something weird here, friends."
2) You only deserve equal pay if you do equal work
This is also true. But what is equal work? Have you ever met two people, in any industry, in any job, who worked equally? Salaries are very arbitrary, with lots of human intervention and variability. You can justify just about any difference in salary. So let's say I take two months off for maternity leave, and another guy at my office takes two months off for a knee replacement. Are those two absences being looked at equally, or is mine interpreted as "another woman letting her family get in the way"?
What I'm saying is that it's very easy to dismiss a complaint as "well you aren't doing equal work". Again, it stops the conversation.
When feminists talk about equal pay, all we're really asking to do is talk about it. We already did the easy stuff... we made it illegal to discriminate, and to arbitrarily declare a job as being for men or women only. And today, all we're asking is to do more easy stuff... extend the statute of limitations, allow people to discuss salaries.
We look at the big numbers, the fact that men hold a lot more wealth than women in this country, and we ask questions about it. Since the women's movement began, people have tried to shut us up by saying "that's just the way it is". Feminism is about saying, "really?"
We are not looking at that average salary difference and saying that it means we all deserve an instant 20% raise. Do not let anyone tell you that. In fact I personally feel that I have never experienced wage discrimination... but I'm in a privileged world. I'm obligated to bring this up for other women.
We just think it's funny that when the complicated questions are posed, we end up with fiascos like the 2011 Wal-Mart case where OH LOOK SHOCKING, there was discrimination everywhere! Hearing that equal pay is a non-issue after that is like lifting up one rock, finding a bunch of nasty worms underneath it, and having someone tell you there's no need to lift up any other rocks because they're all clean under there.
Lots of times anti-feminists claim to be "equalists" - here to help all humans! Well fine then equalists, how would you explain the wage gap in a way that could actually reduce it? Or do you just not have a plan? That's the feeling I get from the other side.