1) A offers to sell laptop for 2000 bitcoins, and escrows 2500 bitcoins as security
2) B offers to buy and escrows 2500 bitcoins
3) A confirms that item is sent but never sends it
4) B never receives it so never release the bitcoins
5) A now cares because he has 2500 bitcoins in escrow as security
In this scenario, it's in A's interest to send the laptop, otherwise he loses his BTC 2500 security. It's also in B's interest to confirm receipt of the laptop, otherwise he loses his BTC 500 "excess".
The awkward situations are going to arise if both A and B are honest, but an uninsured delivery service loses or breaks the laptop, or if one of the participants dies before releasing the escrow.
That sounds promising.
Am I right in saying after step 3, both parties are committed and if either defaults, BOTH parties are on the hook for 2500?
Let's assume it's B whom is fraudulent. Although B has gained nothing more (in fact paid 500 over the asking price), he's still managed to defraud A of 4500 - a great way to put the opposition out of business if you have the capital to do so.