There's very good reasons why Apple doesn't trust it and does something different. When so much of the phone security relies on it, it's very important to get it right.

https://www.google.com/amp/www.slashgear.com/android-soc-sec...

The "trustlets" that run in the TrustZone have enhanced privileges and must be securely written. Once crap like DRM ends up in there, as it invariably does, it turns actively harmful.

http://bits-please.blogspot.com/2016/05/qsee-privilege-escal...

The design and implementation surface area for TrustZone is just too big to be secure.

Protecting a few secrets is a bit different from a Quasi-hypervisor environment that could be used to implement such a scheme.