What is the exact collision boundary of BoxCollider2D?

Hi, i’m Unity beginner.

Currently, i’m trying to make a small game using Unity. But There is a part that I don’t understand while making the code related to the collision.

There is Two object with BoxCollider2D, RigidBody2D, and Test01. I want to accurately detect when they collide. Both BoxColliders have IsTrigger applied.
The code for Test01 is as follows.

When playing in Unity Editor, collision event function was executed even though the colliders of the two objects were separated. Why does this happen?

I want to check the collision point of the object with some accuracy, what should I do?

p.s. When using CircleCollider2D instead of BoxCollider2D, the OnTrigger event function ran more precisely when the two colliders met. Why is BoxCollider2D so inaccurate?