The "entry barrier" and the level of commitment required to bring an OSS project to "findable in Google, has at least some github stars/whatever equivalent, is green in CI, and actually works when you try it" is higher that the authors of a typical internal library in a typical enterprise can afford. Which is why the recognition and trust is usually higher. All IMHO.

Sure, but if you search on Bing or Duckduck go, you will find them. This one is purely because google search quality went down so much in recent years, that it cant find anything niche - even if you add literal quote from what you are looking for into the search.