> you already have buggy compilers and buggy OSes and buggy libraries.

Which run, I must add, on effectively infallible hardware. Most of the software straight up assumes that the CPUs and the RAM will function perfectly and don't bother even trying to detect such failures (unless those failures manifest themselves in a catastrophic manner, the show will simply go on).

So in effect, we also can, and do, build less reliable systems out of more reliable components, and that's how software is different.