I still don't understand how this helps though - couldn't the person still get their shipment and claim they never received it in order to trick the middleman to return their funds?
How does the middleman have any ability to investigate or know who to believe?
In one model of escrow, the middleman receives both the goods and cash before distributing them to the other parties. Potentially doing some inspection of goods at the time too.
In another model, more common on the internet, the middleman holds the money from the buyer while the seller ships the goods to the seller. They can't guarantee the buyer does not lie to the middleman, but it changes the incentive structure around fraud. Especially so when the middleman runs or has connections to the marketplace.
How does the middleman have any ability to investigate or know who to believe?