However it is also worth considering that apples to apples is hard to compare and may have a latent bias you accidentally brought up by adding the adjective "senior". What if, and this is what I've seen, females tend to promoted and said titles slower/later. So a 32 year old female may be stuck at non-senior $180k while the 32 year old male cohort she started with got the senior title 1/2/3 years before and is at 220k.
Some of this is still of the same flavor of "not demanding it" as aggressively as a male might.
Otherwise, yes most of the time people point at far bigger pay differentials in stats that are driven by apple/orange compares like comparing male majority SWE jobs and female majority teaching/nursing jobs, which duh, high %% difference.
If they're actually working in the same jobs, wouldn't this discrepancy show up in the statistics? If all the male senior developers are driving a hard bargain and getting $220k, but the female senior developers aren't and are only getting $200k, it'll still show up as a 10% difference in an apples to apples comparison. The fact that such apples to apples comparison shows minimal difference either means such effect is tiny, or there's a bunch of effects working for females that's canceling out the "males bargain better" effect.