Why? Is there any way to be certain these are done in hardware and can’t be caught in a low level system once the device is rooted? It’s a black box, so no way to know until somebody manages to pull it off.
I can implant a tiny microchip into your phone that will intercept every disc read/write and transmit it. Is that something it makes sense to check for, though?
These days, it's easier to thwart the Evil Maid attack, as it's known, by replacing the device, and some recommend doing that when entering/exiting China, attending DefCon, and a few other scenarios where it's credible under a given threat model. Most of us aren't Edward Snowden, but are still cases where thats not so ludicrous. The FBI has installed keyloggers into laptops supposedly fresh from the factory that have been discovered before. It's not just specific person devices, either. Aspersions were cast on Supermicro motherboards installed into Cloud provider data centers, even if nothing was ever found/proven.
