The reason people are weary/leery of Traveller's Checks is that many, many times the people go home and file a lost or stolen claim with the issuing bank or institution. This eventually comes back to the local agent who cashed the check in the first place.
If there is no reliable backup identification, the cashier is held for the money.
This scam has occured many times in Sosua, and I imagine in other places.
HB