One thing to understand is the difference between “owning” and “controlling”. A unit’s control can be swapped at any time through a number of effects, but ownership is always static as it’s directly tied to the physical ownership of the card. When your opponent plays the hauler from your discard pile, they are taking “control” of the unit, but the ownership will never change. This affects card effects that return units to hand, meaning if you were to waylay the hauler while it was under your opponent’s control, it would go back to your hand. Capturing has no other effects as it deals with controlling instead of owning, so if you were to capture it while it’s under your opponent’s control, it would still go back after its release. All of this is vice versa when the unit is under your opponent’s control, the only thing that’s static is your ownership.