Cuz he doesn't care/doesn't want to know. Takes the fun out of it, he'd no longer be Batman, he'd just be some guy https://twitter.com/ActorsCentral/status/1259571887514030087

Now then as for how the hell the public didn't put 2 and 2 together when Bruce's adopted son vanished around the same time Robin stopped hanging out with Batman, I dunno, the people of Gotham are idiots

Comics are stupid and so are the people inside them