I scheduled a 730pm flight. My plans changed and I showed up at the airport at 1pm in an attempt to fly standby.
The gate agent told me that there were seats available on the aircraft that was boarding and they would be happy to let me board if I would pay the difference to the full price fare. The difference was about $300.
I asked for clarification on the policy and the agent explained that the company would allow the plane to fly with 1 person on it rather than allow paying passengers to board an earlier flint without a full price ticket.
I called Southwest customer service and they confirmed this was their policy.
Southwest now joins United as one of my least favorite airlines. They've lost my business unless I have no choice but to use them.