The premise of every gritty Batman reboot is basically the same: what if we took this seriously and made it realistic? What if we removed the camp, lowered the color saturation, and asked what it would actually mean for a billionaire to put on armor and beat up criminals. Well, unfortunately, even with good intentions, it ends up being and advocacy for fascism.
The realistic Batman is more than a vigilante in some vague morally gray way. He is a private autocracy. Before discussing, I'd like to point out that I assume you know Umberto Eco's ur-fascism, at least his famous 14 properties of Fascism. I'd suggest reading them beforehand, if not, since they're great work on defining fascism ideology.
Batman, in a nutshell, often checks: distrust of legal process, the enemy defined as a standing justification for extraordinary, illegal, measures, and the conviction that the right person may use violence outside the limits that bind ordinary people. Once you ask what Batman looks like without comic-book distance, the fit becomes difficult to miss. He does not trust institutions, he decides who the threat is, and he answers to no one because he believes his judgment outranks the system. The armor is the proof. When Batman fights against super-human threats he is usually justified in his methods and extremism. When you make him "realistic and gritty" and put him in a normal city (yes, full of crime, but still real-life like) with normal people, those same methods end up being the same tools that fascists governments use to keep people in check.
The Dark Knight Returns. And Rises
Frank Miller's The Dark Knight Returns remains the most honest major treatment because it does not hide the authoritarian charge inside the fantasy. It stages it directly: Reagan is in the text, Superman becomes a state instrument, and Batman is shown as frightening, excessive, and politically loaded. And the story does bend backwards a bit to show how he's justified. The enemies are literally . The book does not solve the contradiction so much as make the reader sit inside it. That is why it still has interpretive force. Miller drew what he was drawing and did not pretend otherwise.
The Nolan films want the realism and the moral escape hatch at the same time. The clearest example is the sonar surveillance system in The Dark Knight. Batman turns Lucius Fox's technology into a mass citywide surveillance tool. The movie bends over backwards to make sense of Bush's surveillance apparatus. Don't get me wrong, I wouldn't consider Bush's government fascist, but the surveillance system was definitely a datapoint to make a case for it.
Fox objects, calls it too much power for one person, and agrees to help only on the condition that the system will destroy itself once the Joker is found. The film wants the audience to feel both things at once: the intoxicating reach of total surveillance in righteous hands and the reassurance that a good man used it only once. That is an interpretive dodge, not a resolution. The political problem is not erased because the exceptional man promises to stop.
I think this darker realistic aesthetic keeps returning because the fantasy itself is durable: institutions are corrupt, procedure is weak, the enemy is close, and the right man must act, and laws are holding them back. Look, I grew up loving Batman. He was a knight in shinning armor... well a dark night if you must. But reflecting on it, a real life Batman would turn dark fairly soon, and the stories we got trying to make it realistic end up making him a justification for fascism. Perhaps it's better to keep Batman fighting super-human mutants that the police cannot deal with. Perhaps that is when the character was at his best, when he used his intellect to solve problems, not his fists. When he was an intellectual, a detective, not a brute.