Dinah Laurel Lance has a long history with the Bat-Family. She's even in Batgirl's Birds of Prey when they're together. But she's more than just a team player.
In one series, Dinah and Bruce were actually raised up together in their superhero training by the Justice Society of America. Other times, Batman trust Dinah to do things he knows other members of the Justice League wouldn't be comfortable with doing. Like talking to kids.
Batman has always respected her skills, and always accepts her help when she offers it...and he feels he needs it. Add that to her friendship with other Bat-Family members, and Black Canary is a true ally.