I think the low-tech solution is the correct one in this case. If one wants to be sure their camera is not recording them they can a) audit the entire source code of their OS and relevant applications (including the complete chain of compilers that have ever been used to compile compilers for their device all the way back to the very first one), device firmware, and inspect the circuit layout of all integrated circuit devices in their computer to look for backdoors or b) they can put something in front of the lens.

I agree that this is a pretty regrettable state of affairs that we basically can't trust anything with a turing-complete processor in it somewhere.