Ridable entities that can be steered build up fall damage when on climbable blocks.

If you ride a pig or strider down a ladder or vine, fall damage is built up.

This only works when you holding the mob's corresponding item to control its movement. (like a carrot on a stick)

One way to test is by riding the mob down a large wall of ladders, looking slightly away from the ladders to travel downwards. Once you reach the ground the mob takes a lot of damage. If you are in survival, you will take damage as well.