Because we are extremely simple and self obsessed animals in the whole. At the intersection of those two things, we regularly conflate base familiarity with earned trust. A bit of a narcissistic drive to tell ourselves that… if WE know about something, it MUST be good, otherwise we wouldn’t have taken the time to first learn about it!

It’s why your town is currently infested with hands-free signs in every public space. It’s also why incumbents have such large advantages in elections and why dead/convicted politicians (or Last-name sharing family members of those politicians) are often elected after the fact.