What counts as willing movement?

So this is something I just found out about that I find odd:

  • Opportunity attacks—trigger off of movement that uses the creatures movement (action, move action, bonus action, reaction.)
  • Sentinel—Whenever a creature within 5 ft of you makes an attack at a creature other than you.
  • Booming blade—If the target willingly moves.
  • Mental Prison spell—if it moves, attacks through it, or reaches any part of body out of it.

So the “willingly” is different than other rulings for how effects related to movement works. However what exactly fits willing?

  • Cause fear—nope magic is having them move.
  • Dissonant whispers—same thing. They have to immediately move.

So the creature has to want to move completely of its own accord.

  • Crown of Madness—Humanoid creature you choose must make a wisdom saving throw. On a fail it is charmed by you. (Next is flavor text so skipping.) While charmed in this way the target must make an attack on a creature other than itself that you mentally choose on each of its turns before moving. It can act normally if you choose no creature or if none are within reach.

Crown of madness isn’t making them move but doesnt specifically say willing. And if the ruling for willing is movement not caused by magic what about magic causing situations where you take damage if you don’t move. Would a creature shimmering with evocation energy be spared because he moved out of the magical blender that is cloud of daggers? If no, then what is the go-to rule for willing movement that I should be using?

In short, what movement counts as willing, and where can it be found? Is moving out of obvious danger caused by magic, willing? Is moving away from an ally so you don’t hit them, willing?

If there isn’t any actual ruling on willing, that’s fine; I’ll go back to running it with my interpretation, so that it has same wording as AOO. If there is an actual 5e term or explanation for willing (that isn’t Sage Advice), please let me know. I just don’t see why it was necessary to put a term in the spell that isn’t used anywhere else. I understand it could have been overlooked since it was in a splatbook or has just been ignored since most people probably assume that there is “Forced ” and “Willing” movement, with the willing being defined as: any movement from an action, move action, bonus action, or reaction. In same way AOO work.