I've had similar philosophical thoughts about a transaction rollback.

Consider this definition from go's database/sql package.

    func (tx *Tx) Rollback() error

Rollback can fail, indicated as such by it can return an error. What are the cases where rollback could fail and what's the recovery mechanism? Does a failed rollback mean (logically) that the transaction is still open and uncommitted? But really, invoking rollback can never fail to abort the transaction, so the error result has little use.

Now, obviously the error isn't totally useless as an error can be returned to indicate, say, the connection to the database was dropped. But even in that case, the definition of a transaction's validity/lifetime means that even if rollback fails, the transaction is in the same state as if rollback had succeeded.