Why do actions with class and public method don’t fire __construct()

I’m trying to understand how WordPress works with actions, classes, and methods.

If there is a class “TestClass” and it has a public method ‘method1’

The method can be hooked to any action as “add_action('theHook', ['TestClass', 'method1']);

From my understanding. If you don’t initialize the class, you can not access its public methods and objects.
Now, I would assume that WordPress has to follow this, and it must initialize my “TestClass”, which will cause for public __construct() to fire.

However, after testing this, it does not fire __construct()..

Why is this?. I know a fix would be to self initialize inside ‘method1’, but I’m trying to figure out why WordPress behaves this way.