It's especially hard for embedded software. You certainly do want hardware-in-the-loop tests, but you also want tests that are independent of the hardware. You have to simulate the hardware interaction, and you definitely want to verify what the code tried to do to the hardware, and when. So for the hardware-interacting layer you want mocks, not just fakes.
Just imagine a world where a component manufacturer (be it hardware or software) also provides a verified fake/simulated implementation.
Even hardware, they likely did develop it using software simulations: they just need to ship it with their SDK. Another thing hardware has it going for it is that it does not change as much.
Note that a verified fake could still have observability points that allow you to monitor what's going on.
