Titans is bringing Robin the Boy Wonder to live-action properly for the first time since Batman and Robin, but Batman is not expected to make an appearance, and Jason Todd could be the perfect intermediary. It's not that Batman isn't going to have a presence on the show - Robin's very existence proves that fact, and the newest trailers include a ton of Batman references, but in order to work, the show will need a way to give Robin a history, backstory, and relevance, yet not let the whole thing be dominated by one of the world's most famous superheroes.
Supergirl on the CW ran into a similar issue. The show started off constantly making nods and winks toward Superman, being blatantly obvious that Supergirl does in fact occupy the same world as her more famous cousin, but he was mysteriously absent at first, forcing the show to constantly explain why Superman didn't just solve all National City's big problems. Superman would eventually make an appearance on the show, making his absence at other times a little less awkward, but there's still that looming red cape, making the show constantly aware of that same question: "Where's Superman?"
Titans was doomed to suffer the same question for the World's Greatest Detective, and they're addressing it in a couple smart ways. First of all, the problems Robin faces are far less significant than those of Supergirl, so it's totally plausible that Batman wouldn't need to get involved, but that's not the only reason Batman and Robin aren't fighting together. As anyone that saw Robin's "F*ck Batman" line from the first trailer could surmise, the former Flying Grayson isn't exactly on speaking terms with his former mentor.
As has been revealed in trailers, Robin is resentful of Batman and fears he was becoming too much like him, so he left Gotham to become a detective in Detroit. This creates both physical and emotional distance from Batman, but as we know from the marketing, he's still not entirely severed his connection to Wayne Manor and the Batcave, as he has an encounter with his replacement, the new Robin, Jason Todd.
As the show goes on, it only makes sense that Dick Grayson will eventually come face-to-face with Bruce Wayne again, but bringing in another Robin in Jason Todd gives them yet another narrative tool to keep Batman at arm's length. If Dick and Bruce aren't on speaking terms, and Jason serves as a sort of intermediary, it's now possible for Dick to actually interact with Batman - in a way - through Jason Todd, allowing the show to continue avoiding giving the Dark Knight any screen time.
Considering how much of the show's casting leaked before official announcements, such as Curran Walters' role as Jason Todd, it seems like any sort of Batman casting would have been leaked or announced, unless he's kept to an absolute minimum, appearing only in shadows and flashbacks with minimal dialogue and a season-ending cameo at most. Surely a proper Batman appearance could be complicated on a show with a budget like Titans', so the fact that a full DC Universe and Robin are able to be crafted without leaning on the Caper Crusader, allowing Robin and friends to shine on their own, bodes well for fans of the Teen Titans, and hopefully Batman doesn't have to swoop in to save the characters or the show itself.