Alright, perhaps there were some misunderstandings here. I just don't interpret tieflings as being as hated as you make them out to be. Not because they don't scare people, but because msot settings have so many worse things out there that tieflings kind of move to the background in the grand scheme of things.
to give an example, joe the peasant could waste his time on chasing a tiefling that just wants to be left alone off of his land, or he could fortify his door against the nth squa of bandits that started plagueing the countryside.
Or slurring when they're speaking with their friends. Those sort of mistrust.