Hello, i was wondering why didn't the vehicles Shortcut Action (where Opposing Piloting check is included) appear in the AoR Core Rulebooks list of Vehicle Actions?

Is it replaced by the Chase , thus transforming it into a Free Action? Because in Chase you only make Piloting Checks without spending actions

Shortcut isn’t an action. It’s a talent, and a passive one at that, which grants additional boost dice to your checks to either evade or catch up to your opponent during a chase. The Improved version of the talent adds automatic successes instead as an incidental.

In the Beginner game, it is introduced as an Action where an Opposed Piloting Check is made between the two pilots (PCs and Sarev escaping)

thus my confusion

Yes, the Shortcut Action of the Beginner Game is basically replaced by the Chase Rules.

I'm afb, but wasn't the Shortcut Action of the Beginner Game just an opposed piloting roll? You can still have them in situations where you don't want to have a big chase scene, since in the full rules opposed checks are still available and important.