I only have limited experience with 737-4/500 and A32S. On the 737, OWL was forbidden, unless commander decides otherwise as Capt. Claret describes. On the A320 the situation is the same, but like an icing on a cake, QRH contains an OWL checklist, OW circle-to-land with one engine inoperative data and pilots are trained to do so. That may be course specific The important thing is to make an entry into the tech log because inspection is required. I have been told that unless the touchdown vertical speed was above 460 ft/min (which is rather heavy landing, but maybe my memory fails me) visual inspection will suffice.
At first, I was stunned how "good" the A320 is compared to 737. But if you give it a deeper thought both are certified along the same rules so structural margins could be the same. Maybe all the difference is the manufacturer's decision to equip pilots with a tool to deal with such non-standard situation.
Also, at MTOW and quick landing with 500 kg less A320 comes 16-19% owerweight. I would guess that other small jets are about the same and hence fuel jettisonning is not installed. I wonder what would be the ratio for the widebodies. Is it at all possible to land a 747/340 at MTOW -2t ?