Then search engines must not be legal. They crawl the public internet and index what they find. What you’re effectively saying is that the flyer is unknowable

Then search engines must not be legal. They crawl the public internet and index what they find. What you’re effectively saying is that the flyer is unknowable unless a Street-view car drove past and snapped a picture of it and its owner engaged in SEO to make sure it landed near the top of search results. There is no “house” in this analogy (which you might call a corporate/private network secured or otherwise). No private network was accessed. This stuff was on the street, in the free pamphlet section of the newspaper stand.