Too Japanese for Me: when the truth doesn't matter because no one tells it

So I'm watching shojo anime La Cordo de Oro when it happens again. I find myself saying, "Not again!  Are you kidding me?!" as the heroine, betrayed by a jealous and shrewish lying liar of a comrade, refuses to tell the truth to those in authority, preferring to take the unfair reputation hit herself for some (probably obvious to Japanese) reason.

My next thought is something along the lines of "This is why I am not a shojo heroine because if I was, I would tell the truth and let justice be done, and then later on when I needed to be helped/saved, there would be no people I had graciously helped to assist me."  (That sort of thing where justice is served and the villain is redeemed to come back and save the hero seems to happen in shonen manga and usually involves fists as a definition for justice.  [Dengeki Daisy is an exception in this case, but DD is, well, an exception-al shojo manga in so many ways.])

It happens again a little later.  [SPOILER] One of the reverse harem members misses a performance because a jealous enemy locks him in a closet.[/SPOILER]  At first, when it could have made a difference, the kids don't explain, but later it sounds like they tell the authorities, not that it makes any difference for some (most likely obvious to Japanese) reason.

I just don't get this.  Is it simply a shojo manga trope, or is it really a reflection of some inherently Japanese cultural mindset/characteristic?  If so, which one?  I find myself very curious.