Danny didn't want to know who the fuck Bruce Wayne was, but Sam's parents would not shut up about the guy as Danny was growing up.
So, yeah; he can recognize Bruce Wayne on site. And his children.
Not because he stalked them! It was all Sam's fault, her and her parents! Her for complaining about the Waynes, and her parents for idolizing them!
Anyways, he's pretty sure he just saw some chick drug Dick Grayson's quadruple sugar caramel frappe, and Dick drank it.
Danny doesn't really think? He kind of just moves.
Dick Grayson barely gets out a "Uh, hey-?" before Danny decks the bitch in the face hard enough to throw the woman back five feet.
She's definitely going to need a hospital.
Danny doesn't give a fuck.
Danny gives so little fucks that he just puts a very carefully gentle hand on Dick Grayson's shoulder and steers him away from the scene.
"She roofied your drink. I'm taking you to the hospital."
Or; Dick was going to allow a Trafficker to drug him, so that he could play bait. The trackers he'd swallowed would absolutely lead Jason to where he was taken, as Jason was working with him on this, but didn't meet the traffickers "type". He didn't tell Bruce he was going to do this. So when the Rohypnol starts to kick in, he's absolutely sure he sees Bruce come in out of nowhere and wreck the Trafficker's shit. The randos filming the incident think they just saw someone's dad almost murder a bitch, and then heard said dad mention roofies. When the videos are posted online, and the dad is "identified" as Bruce Wayne, Bruce has three things happen. First; he's getting a lawsuit from the woman. Second; he's also getting notified through this that he has a doppleganger or clone. He will need to investigate, as he needs to thank the man. Third; his image has become pristine in the eyes of Gotham, and has also become yet another wholesome meme.