I think a larger percentage of society would be willing to call this "structural gender-based inequality" rather than sexism, because most people including myself use the word "sexism" to refer to a belief that one sex is less capable or somehow worse than the other.
Similarly, men live fewer years than women, and so receive less retirement benefits. This is a structural gender-correlated inequality (maybe gender-correlated is even better than gender-based) but I don't think many people would call it "sexism against men". They would just say "oh, yeah, that's odd... maybe we should adjust that now that you've brought it to our attention".