Well, interestingly the "trust factor" is actually sort of irrelevant for PWAs. Because PWAs don't have access to that sort of features (e.g. a PWA can't read your text messages or contain malware), they don't need third-party vetting (or at least not more than any standard website).

And that's the whole point, actually. By allowing apps to reside on the web directly, we remove the need for intermediaries (besides the browser). The web is beautiful in that regard.

I agree, however, that this fact may not be obvious or intuitive for most people (yet).