That's because you could directly observe it, which only takes place here and now. That is science.
No.
So then, let's say that a man punches you in the back when you're not looking. You turn around and accuse him of it, but he denies he did it. But you and him are the only ones there.
You turn around again, and then you feel him pull your hair. Turning to face him, he denies he did it. You then point out the strands of hair in his hand, strands which are the exact same color as your hair. He still says he didn't do it, and you can't prove it because you never saw him do it.
You turn around again, and the you feel a needle poke into your back. You turn around, and the man is holding a needle, with blood dripping off of it, and you have a needle-sized hole in your back, bleeding. But the man still says he didn't do it, and you can't prove it because you never saw him do it.
Then the man takes out a gun. But he assures you, he won't shoot you. After all, he has never harmed you before, why would he harm you now? He says this with an evil grin on his face as he loads the gun and aims it at you, then tells you it's okay, nothing will happen, just turn around.
I take it you would believe him?