The figure is true only insofar as it is used with all of the appropriate caveats. It's a figure about the total earnings of full time workers, not about equal pay for equal work. The figure is important when looking at society as a whole—"why are women being pushed towards lower paying fields?" and the like—but isn't applicable on the individual employer level.

When you do look at equal pay for equal work women still come out behind. It's a much harder topic to research since quantifying "equal work" is difficult, and it's a much smaller gap since this is only one of the things that leads to an overall pay gap. However, it is widely believed among experts that a gap still exists.

This leaves us with OP's brilliant argument for why no gap should exist, juxtaposed with the observation that one does. Where's the resolution? Are the experts secret SJW agents? Is there some conspiracy to try to get women overcompensated for jobs? No. The problem is OP's argument is complete and total bullshit.

The whole premise of discrimination is that it's letting one's prejudices and emotions get in the way of logical thinking. If someone thinks that women are bad at math then they'll require a little extra push to hire a woman for a math-heavy role than hiring a man. Whether this is the woman accepting a lower offer or needing better qualifications, the idea of equal pay for equal work has been broken.

This isn't something where every hiring manager has a vendetta against women. It's likely not overt at all, since most people would be quick to say that they'd never make a decision like this and if it could ever be proven on the individual level then that's a lawsuit waiting to happen. Even good people still have their biases, though, and these biases can cause effects like the pay gap on a societal level.