Personally I actually cared significantly more on top of being the one who had to work a full-time job and side gigs, but my ex is a unique kind of piece of shit and I'm not trying to insinuate that this is a common experience.
But your original comment sounded like something my ex would say when she still allowed me to go to the office. "Oh you get to take a break for 8 hours." No I don't, that's still work, it's still very taxing mentally. If you work for 8 hours and then come home to take care of the children for the rest of the evening so your partner can have a break, there's only one person actually getting a real break. Of course if you come home and drop yourself onto the couch and expect dinner to happen, then it changes who the person getting a break is, but IMO that's not as common among young families these days, compared to a few decades ago.