[brvs]

I would care if they were present. But I have no positive evidence that my computer is infected by any of that. I don't need to manually scan through C code to feel safe. Just like I don't have to watch my food being prepared to be sure it isn't being poisoned.

[kyrias]

The point is that neither you nor anyone else could check for it if you/they wanted to.

[nwh]

Malware would have to be fairly stupid to reveal itself to the end user.