‘“They don’t even know to turn cups upside down to drain,” a housewife once told me in wonder.’
... and they don’t know that because some coddling parents, probably from that housewife’s generation, didn’t bother to make their snowflakes do any chores.
No, more like, their father never married their mother, and mother’s career came first. They raised themselves as best they could.
If you dry the cup immediately after you wash it, you don’t have to “drain” it. If you don’t do it immediately, you leave it sitting in the sink (upright or inverted) and never think of it again.
If we had a talking parrot, it would bellow (among other invective), “WASH! DRY! RINSE! PUTAWAY! NOW!”