No, that's a very valid question and a bit of a conundrum. An intriguing new idea might explain it indirectly - the idea is about the gospel of Mark and the technique of Mimesis. Since Matthew used Mark as a source, it most likely was just copied out of Mark.
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Review of The Homeric Epics and the Gospel of Mark
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(by Dennis R. MacDonald; Yale University, 2000)
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"MacDonald begins by describing what scholars of antiquity take for granted: anyone who learned to write Greek in the ancient world learned from Homer. Homer was the textbook. Students were taught to imitate Homer, even when writing on other subjects, or to rewrite passages of Homer in prose, using different vocabulary. Thus, we can know for certain that the author of Mark's Gospel was thoroughly familiar with the works of Homer and well-trained in recasting Homeric verse into new prose tales...
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"Once the evangelist linked the sufferings of Jesus to those of Odysseus, he found in the epic a reservoir of landscapes, characterizations, type-scenes, and plot devices useful for crafting his narrative" (p. 19). Of course, all throughout MacDonald points out coinciding parallels with the Old Testament and other Jewish literature, but even these parallels have been molded according to a Homeric model in every case he examines. Consider two of the many mysteries MacDonald's theory explains, and these are even among the weakest parallels that he identifies in the book:
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* Why do the chief priests need Judas to identify Jesus in order to arrest him? This makes absolutely no sense, since many of their number had debated him in person, and his face, after a triumphal entry and a violent tirade in the temple square, could hardly have been more public. But MacDonald's theory that Judas is a type of Melanthius solves this puzzle: Melanthius is the servant who betrays Odysseus and even fetches arms for the suitors to fight Odysseus—just as Judas brings armed guards to arrest Jesus—and since none of the suitors knew Odysseus, it required Melanthius to finally identify him. MacDonald also develops several points of comparison between the suitors and the Jewish authorities. Thus, this theme of "recognition" stayed in the story even at the cost of self-contradiction. Of note is the fact that Homer names Melanthius with a literary point in mind: for his name means "The Black One," whereas Mark seems to be maligning the Jews by associating Melanthius with Judas, whose name is simply "Judah," i.e. the kingdom of the Jews, after which the Jews as a people, and the region of Judaea, were named.
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* Why does Pilate agree to free a prisoner as if it were a tradition to do so? Such a practice could hardly have been approved by Rome, since any popular rebel leader who happened to be in custody during the festival would always escape justice. And given Pilate's reputation for callous ruthlessness and disregard for Jewish interests, it is most implausible to have him participating in such a self-defeating tradition—a tradition for which there is no other evidence of any kind, not even a precedent or similar practice elsewhere. But if Barabbas is understood as the type of Irus, Odysseus' panhandling competitor in the hall of the suitors, the story makes sense as a clever fiction. Both Irus and Barabbas were scoundrels, both were competing with the story's hero for the attention of the enemy (the suitors in one case, the Jews in the other), and both are symbolic of the enemy's culpability.
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From
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