Actually, escrow is very dangerous for the seller (at least for gift cards). Just think about it. All the buyer has to do is redeem the gift card and then say "the gift card didn't work."
Then the escrow won't release payment to the seller..
How can the seller prove the gift card wasn't already redeemed or sold to someone else prior? (This is what the scammer would be claiming.) You can't prove a negative. Basically, escrow is the best way to scam a gift card seller.
UNLESS it's a gift card that allows the escrow to view/verify the balance first. Then I could see escrow being useful, because it prevents either party from stealing and running. But most gift cards aren't like this.