My daughter is 37 and has a solid middle-class job that pays as well as a man in a similar position. She does not suffer from this phenomenon and neither did I (age 62). I wonder about this feminist cliche. I’m not sure it always applies. The women I know who make less than,say, their husbands, were ones who opted for several children and long stretches out of the workforce.
The idea of women making less than men for the same work may be true statistically, but individual cases often tell a different story.
My mother had no choice. She was not allowed effective birth control and was unable to work due to childcare responsibilities. This is no longer the case.
Your young niece will have a lot to deal with, but wage discrimination seems unlikely.