No, they really aren't like cash. They are like checks. The people who sell them may assert that they're like cash. But if you spend a few minutes with Google you will find many instances where businesses accepted traveler's checks that turned out to be counterfeit, to have the amount changed, etc. The same is true with cashier's checks. Only cash is like cash. And it's a lot harder to change the denomination on a $10. bill into a $100. bill.