Here's why:
* "Après que" introduces a subordinate clause that describes a completed action. The action described in the subordinate clause has already happened.
* The indicative mood is used for actions that are factual or certain.
Example:
* Après que j'ai fini mes devoirs, je suis allé jouer au foot. (After I finished my homework, I went to play football.)
In this example, "j'ai fini mes devoirs" is in the indicative mood, as it describes an action that has already happened.
Important Note:
There is a slight difference in how "après que" is used with certain verbs. If the main verb in the sentence expresses a doubt, uncertainty, or opinion, then the subjunctive mood might be used after "après que." However, this is less common than using the indicative.