Childcare costs halve or something but they don't go away. You still need care coverage for an hour to four hours every workday, all school holidays, summers, sick days, half days, snow days... and that's assuming your job doesn't operate outside school hours (which in the US change every few years as children progress), or expect you to be on call.
Usually the type of careers with that kind of flexibility are either top of the field or the very bottom, so it feels kind of hopeless, damned if you work, damned if you don't.