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.
Also, companies like Apple are huge, with thousands of staff.
These protections aren't there to protect you from "Apple", but Apple staff.
So for example if someone at Apple has been compromised by a foreign state, they can't copy sensitive customer data just willy nilly. They'd have to jump through a lot of hoops that would be prohibitively difficult.
Google had issues like this in the past where some employees were sending data to the Chinese government. E.g.: information about dissidents, political opponents in Taiwan, etc...
This is one of the reasons Google encrypts even internal server-to-server traffic, because the threat is on the inside of the firewall!
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.