Slitherine

I was wondering why dont LH charging LH or LF charging LF or LH charging LF in the flank dont drop the impacted unit one cohesion level?
My question comes from the direction of "Like for Like" and the hit dice ratios. (where LH/LF do not halve their hit dice in some circumstances).

They do

LF flnak charging LH drop the LH a cohesion also

they must drop one cohesion level
just heavy troop don't loose one level if charging by skirmisher.