How is that a trope? Everybody here who has kids used to not have kids, and all would agree that before they had kids they had significantly more time to dedica

How is that a trope? Everybody here who has kids used to not have kids, and all would agree that before they had kids they had significantly more time to dedicate to non-kid-raising activities. Nobody is saying single people have "nothing better to do". Just that they very often have more flexibility with what they can reasonably choose to do.