You don't have to. Which is good!

But in practical terms there is a lot of trusting of someone/their-code going on. Unless you are reading/understanding it all.

I trust linux more than windows. But I've never read a line of it...

I think their point is that the source being open keeps the developers more honest. Of course there have been supply chain attacks in open source, but that is more probable to be found out than closed source ones. In short, auditability improves security.

The thing is, there's always someone who does read it or inspect changes. It will surface soon enough if untoward things are happening.

And that is what is being trusted.

Not "the code is readable therefore trustable".

More "the code is readable, therefore I trust multiple someones, somewhere will read it or has read it and if they have a concern they will voice it".

Is it the greatest thing to trust? No, but like a lot of things in life, it's the best of the practical options.

It works well for you.. but for average person. No.

As a 20 year old linux user, I do often use ChromeOS or ChromeOSflex. Just works. Beautiful UI. No more pain with webcam or wifi drivers - Yes, these have improved by still one has the pain of dropped packets (realtek wifi) etc. guaranteed 10 hour battery life.

With ChromeOS I just get 4 or 5 second - update - immutable OS. Fedora Silverblue is coming up but still not there.

Congrats, you are trading freedom for some convenience.