[jillesvangurp]

Yep, the reality is that we all rely on hundreds of millions of lines of code of software (mostly OSS) that make up our OS, tool chains, libraries, etc. every day. Basically, it's not feasible to even review a meaningful fraction of a percent of that in a lifetime; assuming you even have the skill level to do such a review. In other words, mostly you are blindly trusting other people to have signed off on something and that those people who you don't know personally did a good job of that.