I agree that the wage gap is mostly a motherhood penalty, but there's still plenty of discrimination taking place. A couple of years ago my husband was briefly made the head of his HR department. It wasn't his usual area of work, and he didn't stay there more than a few months, but in that time he commissioned a gender pay equity study and discovered that when accounting for experience, and other relevant factors, women in his company were making less than men for doing the same job. My friend just got a pay adjustment because her company recognized they had been underpaying women for the same work. I honestly don't think this is rare, even if it's not the only thing taking place.