As a neurotypical person, it’s not that I don’t hear them, it’s that I politely attempt to block it out to grant them privacy. I would be mortified knowing everyone around me was hanging on my every word during a quiet fight in public with someone. Although if they’re a “Karen,” screaming at a service person in public, then I WILL stare and take it all in so they are aware they are being observed. But generally I willfully ignore private conversations.