The simplest reason Glinda did not get on the broom

Every day people go into these deep conversations about why Glinda did not get on the broom.

I have a very simple reason that I don't ever see anyone say: she just saw Chistery's first try and plummet to the floor, now Elphaba wants the first try from the top of the tower where if they fell it is a much further drop and there's two of them.