throwawaaay
But, if the end result is that a man and a woman doing the exact same job with the same perf ratings at Google are paid differently, because the woman happened to be paid less at her previous job - is that fair?
There is a reason that NYC just outlawed companies asking for salary history.
However - it's entirely possible for the inputs into the algorithm to be skewed based on gender, and that's where I think the systematic gap may appear. A person's salary history can be incredibly gendered - women are less likely to negotiate for their first job (even if it wasn't at Google), and that initial gap can follow them for their entire career. Women are more likely to take time out of the workforce to care for family/children, which can result in lower pay when they return. Other companies known for high counteroffers (for example, Uber) may be biased against women and be less likely to give them a good offer. There are any number of reasons why a woman might have less negotiating leverage against Google than a man, and as long as offers are based on these inputs and not strictly on level and performance, it is easy to see how a gender gap might arise.