If a woman, say, washes her hair in the kitchen sink,
I'd assume that whatever hair (falls out and) goes down the drain
get chopped-up by the disposall.
(and thus have less chance of fouling the exit pipe, etc.)
But I ask just in case I'm totally wrong, that, say, hair
is so thin that it just slips past the blades, whole, and
clogs pipes just as it would in a shower that had no special
hair-catching thing over the drain.