There are multiple meanings of trust in this scenario: belief in honesty, and confidence of ability. Eg I can trust you to tell me the truth but not trust you to protect me from a missile.

I trust Apple’s honesty. I don’t trust many attack vectors. Someone could gain access to their data center. E2EE protects that. A gov could legally compel them to provide data. I trust when they say they’ve engineered it in such a way that they can’t currently do it, and that they would publicly cause a scene and legal battle if attempted-as they have before. Accidental data leaks also happen. In all these scenarios I trust Apples intentions but know that nothing is perfect. E2EE adds a lot for me.