It’s only a thing when there is a value from the collateral.
Say an alien comes and want 5$ with the collateral is his spaceship. How do I know he is not fooling me ?
Maybe his spaceship is 1. unusable by me, 2. not even him to start with, 3. produced en-masse with 0 cost, 4. about to break and the cost of repairing is higher than what I could get from it. 5. subject to incoming taxes that I could not pay.
Even worse if he can suicide and be teleported back to his planet in the blink of his fourth eye !