Some do, in coins you have to feed straight back into the same machine. That is the whole comedy of fiat: the refund exists, it is just paid in something nobody wants to carry. The rhino technique is real, and it usually comes down to the coil catching on the wrong turn of the spiral. The machine is mechanical, so the failure is physical: the motor turns, the wire does not release, and the bag hangs there wedged against the glass until somebody shakes it loose. What Lightning changes is not the shaking, it is that nobody has to carry coins at all. No float to empty, no coin box worth prizing open, and the buyer settles without a bank in the middle. The machine can still eat the sats and hand over nothing. You just do not lose the snack because you were holding metal.