@abcdw the point of #FreeSoftware (just like many things in life) is not that the user by themselves, as a single human should understand everything.

The fact that it is possible to audit the code means you can ask someone to check things for you, or you can rely on a community of many interested people to check.

Also, when someone says "I can do for you what you want, but I won't tell you how", it is always a bit suspicious.