Modern families look different than they did when I was a kid. Educational and career opportunities for women have changed, reproductive technology makes family planning possible and for all kinds of couples to become parents, and our economic outlook is overcast at best. This means that in many two-parent households, both parents work outside of the home. In my case, my partner and I both have careers we love, and that means one of us often has to compromise. We fight about it, like most couples do when both parents are committed to their careers.
When my husband and I met, we both had degrees, careers, and had been the "bread-winner" in our previous relationships. My husband's ex-wife had been a stay-at-home mom for a good part of their marriage. I supported my ex-husband though college, and then several periods of unemployment, while he tried to start his career in an unkind job market.
What this means for our modern family is that we don't really follow traditional gender roles and we both do our fair share of what our society has arbitrarily decided to be "women's work." What it also means is that there isn't a "default parent" when it comes to school meetings and doctor's appointments. Honestly, we don't want to do things the traditional way. It's not fair to define roles and responsibilities based on gender just because it's typically done that way, but that also means, we've had to learn to compromise, sometimes, the hard way.