I am aware of that. An untargetted attacker cannot know that there is no authentication. Dragnetting connections where they don't recognize any authentication

I am aware of that. An untargetted attacker cannot know that there is no authentication. Dragnetting connections where they don't recognize any authentication therefore risks detection. That risk to the attacker is not present when observing plaintext connections. . I'm not safe from muggers because I have eyes in the back of my head to see them trying to sneak up on me. I'm (largely) safe because someone else is likely to see them (or catch them on camera) and get them caught.