Maybe it's not "the hardest" job in the world, but it is one of most thankless ones, one that comes with a huge amount of baggage, expectations, cultural demands, and lack of mental/emotional support, even for rich white women. Certainly, poor Black women raising children alone have it much harder, but that's not an equivalency that anybody but you is making.

Women are told that motherhood is the most natural thing in the world for them, and that it will be the most fulfilling. This is not necessarily true, even if you love your kids and being a mom. If you admit this, there is judgment around that as well. You are "missing out" on something vital if you choose not to go that route (something nobody says to men), and will be constantly judged and even vilified for that, but in truth, being a primary care giver of children (which is overwhelmingly still done by women) demands in America that you completely sublimate yourself - something that few other jobs demand.

And you will again be judged and vilified if you do not do that unless you are of the tiny percentage of families where nannies are actually raising the children around the clock. For most women, there are zero "off hours" - you are always on the clock, even when your kids are asleep or at school, because the likelihood that they will still need something during those times is quite high and then you have to figure out how to balance your own health/sleep needs/work schedule with that unplanned contingency. And if you have a child with special needs, or health issues of one kind or another, something that is unfortunately rather common these days, the pressures and prevalence of unplanned challenging situations goes up exponentially.

A paper published in the American Journal of Sociology notes that "Mothers in the workforce experience additional disadvantage compared to women who are not mothers, including a per-child wage penalty. The 'motherhood penalty' may account for a significant proportion of the gender gap in pay, as the pay gap between mothers and non-mothers could in fact be larger than the pay gap between men and women. Mothers also face additional disadvantages compared to childless women and men. Some studies show that visibly pregnant women are judged as being less committed to their jobs, less dependable, less authoritative, more emotional, and more irrational than otherwise equal, non-pregnant female managers."

So, not only are you expected to lose your own identity and to put yourself last, but you are almost certainly going to take a huge hit to your career trajectory, even if you go back to work almost immediately. Mothers are viewed as less committed, less intelligent, and walk the double edge of not being a "good mother" if you stay too late at the office but also of not being a "good employee" if you leave at 5 to go begin the second shift at home - where women will overwhelmingly handle the bulk of feeding, bathing, helping with homework, and putting to bed, etc.

There really aren't a lot of other jobs that come with all these extraneous demands, pressures, and prices to pay. Maybe it's not literally the hardest job (not hardest life, but again, nobody is claiming that), but it's right up there - even for rich white women.

Opining about something that you haven't really studied or even asked the people who face this situation about, well, let's just say that I expected better of you. How something seems to you from outside of your own experience is rarely the truth.