[wtracy]

This is more a limitation of smartphone hardware than of Android. In most phones, calls are entirely handled by the baseband processor, and the ARM chip never sees any of the audio data.

Android doesn't expose it because the hardware doesn't expose it to the OS in the first place.

[varispeed]

I am not sure if that is true. I am running Samsung S9 with an early Android version and call recording works just fine. The Samsung released an update that disables call recording altogether (and does not allow you to turn off updates, so I've been postponing the OS update for almost two years now every day or so).