I'm a developer, and knowing how this is the default is not something I particularly like, but it's really only in the most security/mission critical code that dependencies get thoroughly wetted.
You can fully expect that less then 1% of the apps in any app store has a transitive dependency chain that is fully known and understood by the author to any meaningful extent.
Most of that code is however understood by someone, although not necessarily the app developer. The sandboxing and app permission dialogue boxes are unfortunately a critical part of the defense against malicious code, although not a perfect one by any stretch of the imagination.
You can fully expect that less then 1% of the apps in any app store has a transitive dependency chain that is fully known and understood by the author to any meaningful extent.
Most of that code is however understood by someone, although not necessarily the app developer. The sandboxing and app permission dialogue boxes are unfortunately a critical part of the defense against malicious code, although not a perfect one by any stretch of the imagination.