Apple, Google, etc. have whole teams of talented people dedicated to doing exactly these types of things, and they undoubtedly help prevent many vulnerabilities from escaping the labs. Yet vulnerabilities are still created and exploited despite their best efforts. As long as software is created by imperfect humans, it will reflect the imperfections of its creators.
It's not knowable for any, but it is knowable for some. You just have to build systems that are in the some and are inherently safe. Difficult, not impossible.
I agree, I just wanted to clarify that isn't mathematically impossible to make provably secure systems. It's just hard enough that it's not often done.
