You can choose not to have a child (though caveats around carelessness apply). You kind of cannot opt out of parenting once you have a child. Not if you wish to remain a decent human being. It's kind of forced on you, even more so than a job, because it's much easier to change jobs or just go on a welfare than to stop doing all the parenting each day as a parent throws at you.
Anorexia heard of it. That's what happens if you choose not to eat. Yes you die but it is a choice (ish, a desease? yes, but stil a choice(of madness)).
Being a parent is time forcefully spent. Now one could argue that all free time for a parent of children below a certain age is parenting time,and thus it might make sense to have a checkbox rather than a time slider for parenting time. The point is a parents free time is non existant we simply cannot play games on a pc or code for an extended period of time on weekends or holidays because that comes at the cost of not monitoring your child's daily consumption of soap (it should be zero, but you will be amased), or you could lock them in a padded room (illegal) so that you can code/game whatever in peace.
The point is, a child makes sure that you never have a split second while they are awake to do what you want because they will literally sit on your hands and pull your hair (and you will come to love it in a bizarre way) that's just how it is (for a while)