1. He's Just Flat-Out More Powerful
What it comes down to is this: Superman is just flat-out more powerful than Batman. Yes, Batman has some advantages, but not as many as you might think when you really break it down. As Ive already explained, stealth and intimidation arent much use against a guy with superhuman senses and who has tested his resolve against demigods; being the richest Earthling still doesnt mean much when your opponent has superhuman powers and alien technology; and intelligence and strategy are great provided your opponent isnt also supremely intelligent and can think and react faster than you. When everyone points to The Dark Knight Returns as an example of how Batman can beat Superman, they do so by leaving out some crucial aspects. For starters, Superman was in a weakened state because he had just been at ground zero of
a nuclear explosion! Batman had a massive advantage in that there was no solar energy for Superman to draw on and he had already been through the ringer. Even
then, Superman was holding back. He was monitoring Batmans heart the entire time, more worried about his friends safety than the battle. Thats not to say Batman wouldnt give as good as he got, he definitely would. But this would basically boil down to an endurance trial. By virtue of being a living solar battery, Superman has the kind of endurance Batman just plain doesnt. At the end of the day, Batman is still human, he still has basic biological needs like food, water, and sleep. Superman can go for long periods without these things. Superman could drag out a fight with Batman for a very long time and while Batman would be pushing himself to the limits of exhaustion, Superman would barely break a sweat.