[lm28469]

How do you remove biases from such a process though.

Given two employees, same education, same title, same working hours, same productivity (based on managers reports), nothing guarantee that the HR department won't "like" one more than another. Or one might ask for raises more often or with better arguments (having kids, longer commute, getting offers from other companies all the time).

Office politics are what they are, politics, as long as you have human in the process you'll have biases. Now if these biases are stronger against certain group it probably should be addressed.

[chosenbreed37]

In addition, the more fuzzy the nature of the work the more room for variations between remuneration. I suspect that the gender pay gap is lower workers in warehouses, factories or fast food restaurants.

[hopler]

The gender pay gap is large in restaurants -- women servers get bigger tips.