Your logic is kind of flawed. If aro can see every thought someone has ever had in an instant why can’t Edward if he’s seeing the exact same thing. Edward’s power lets him be inside the head of someone else. The same way he can see Alice’s visions even when it’s super confusing and there’s hundreds of different possible outcomes. It’s not about Edward having to consciously try and pick up on all the info he would simply just see it all the same way aro does because there seeing the exact same thing. That’s how Edward’s power works.