Since I brought it up,kinda, I'll take a crack at it.

Young horses have enough on their minds. Some don't want that bit in their mouth. Easier to throw head up instead of down. Bad habit.

Put a bosal on them it is kind of like getting haltered. They are probably used to being haltered.

Woman tried a bridle & lost the fight.

Yup, I know it doesn't have to be a fight. Time means nothing to a horse. 30 days is 30 days to a human being.