Why is a travelers check considered money while a written check against a trasaction account is not?

Answer 1

Travelers checks are verified or guaranteed funds. To receive travelers checks, you must purchase them. This means the money has been provided up front and so the person who is receiving the check (as long as the check is not counterfeit) knows the check is good. Funds have already been collected by the issuer of the check (e.g. American Express), so you do not have to worry about insufficient funds.

A check written against a transaction account is a promise to pay. You are legally required to have enough money in your account to honor any check you write, but that does not necessarily mean that you have or will. (Although you should not,) It is possible write a check against a transaction account that has not enough or even no money in it - there is no way for the person who receives the check to know that it is good until up to several days after they have deposited it.