Maybe because almost everyone believes that people who are "dare" is just pure myth (I say 'almost', because the people that have different marks ((such as Saegye)) knows that dares do exist) and so they do not bother checking the tongue mark. I was confused at first, too, but I came with that conclusion after reading 'til the end (๑•﹏•)
And, maybee, just maybeee, we often do not look at people's mouth when they talk(we gaze more in eyes or somewhere but not exactly the mouth) so yeahh, they don't bother checking the tongue mark at all.
No one ever goes to the doctor. Ever.
It was just my own thoughts ahahaha, well, this is just fictional, we can never know unless we ask the creator himself how did that happen
Maybe it's not as prominent as the author drew it like it was made so obvious so that the readers could see it but for there characters it's not as obvious idk tho
Only problem with that is the one woman sticks her tongue out in front of an entire audience and they see it.
Oh ya I forgot about that haha I have no idea then
just one simple question, how the fuck did absolutely no one notice such a prominent mark on the tongue???? like how.