What if the pay is equal for like-for-like jobs, but for the higher paying jobs one sex is vastly underrepresented? Not saying it is, just that discrimination and bias often runs deeper than some simple comparison.
And if we believed that this was the cause, you'd need to think that Googlers were wildly off the norm in terms of ability. They've got like 90000 employees. They aren't exclusively hiring mega geniuses.
If the data found an actual issue like this, the it would need to be addressed, but at the moment simply claiming that women are paid less doesn't offer any solution apart from paying women an extra 20% across every single job.
What if one sex takes more paternal leave than another so the other sex spends more time in the office improving skills?