On Earth, for some who take a global Earth for granted,
those in the north see the stars circle Polaris counterclockwise
and in the south the stars are seen to rotate clockwise.
Isn't this impossible if all live on a flat Earth.

I've seen demos that do show that it can and does work that way on a flat earth.
Yes, flat earthers are well aware of this phenomenon and it doesn't bother them at all.

It's a bit more complicated than demonstrating super easy stuff like "a spherical rock covered in dust doesn't illuminate like the moon" or "we can see to far" or "radio waves go too far". Those are open-and-shut cases, and can be grasped by all.
Other evidence is much harder to explain (for the teacher) and understand (for the reader or student).

But if your cheating wife or lying friend tells you 10 statements, 2 of which you KNOW are false, but 8 of which you aren't sure about -- why not focus on the 2 easy ones? After all, "Falsus in unum, falsus in omnibus".  Why spin your wheels, perhaps fruitlessly, trying to figure out or prove the other 8?
If you're false in one thing, you're a liar and the rest doesn't matter. Once you've achieved "falsification", the whole thing is falsified. The rest is just gravy; icing on the cake.

It's similar to the reason why heretics are condemned for denying *one* dogma of the Catholic Faith. It all holds together; deny one dogma and you are denying the Faith; you must be condemned. A heretic holds the Catholic Church to be a liar. The Church puts forward ALL of its dogmas EQUALLY. You either accept the authority of God's Holy Church or you don't.

If you have proof that Jane Tranny is actually a man, say because of DNA evidence, all the other arguments and controversy is little more than a distraction. It doesn't matter WHY, HOW, or anything else. It doesn't matter how he got the surgery, who helped him, who funded it, why he wants to be a woman, or anything else. It doesn't matter if he makes a better woman than man. It doesn't matter if he acts more feminine than many actual women, or how many he's fooled over the years.
The fact is: He can't be a woman, he is biologically a man, and that is that.

FACTS ARE KING. Feelings are lucky to be allowed in the room -- and when they are, they are to be silent, keep their eyes cast down at all times, be on their knees at all times, and never turn their back to the king.