For the same reasons merchants, who cut down trees for wood, only get plant
lore 50%. They don't need any more. Merchants dont need to pick the exotic,
rare plants like hemlock or nightshade or what have you, and don't need to
train the skill over 50% to know all the trees. Cavaliers are, classically,
horse-riders. They don't need the higher percents to ride things like giant
slugs or eight-legged banana monsters to use their mounted attacks. Therefore,
they don't get access to those higher percents. Neither will knights. It's a
beastmaster privilege.

Shinarae Lluminus