Why does the Torah omit the word Nasi from the first three tribes (Yehudah, Shimon and Binyamin)?
Or ha'Chayim #1: Because of their proximity to the words "Nasi Echad Nasi Echad" it was not necessary to insert it.
Moshav Zekenim, Or ha Chayim (both citing R. Nisim Ga'on): It was not necessary to mention "Nasi" with regard to Yehudah, because it is obvious that Kalev was a Nasi. It did not mention it by Shimon due to the episode with Zimri. Even though he died, they did not have a Nasi again 1 ; most of the sinners were from Shimon. It was unnecessary to mention it by Binyamin, since Elidad was alias Eldad, 2 who was a Navi, 3 so it would belittle him to call him a Nasi.
Or ha'Chayim #2: It mentions Nasi neither by Yehudah, in deference to kingship, which emerged from Yehudah, nor by Binyamin, since the first king came from him. And it does not mention it by Shimon like R. Nisim Ga'on said (due to Zimri's sin, they were not worthy to have a Nasi).
Riva (25): Kalev [of Yehudah] was already called Nasi (13:2) when the Meraglim were sent. It is not said about Shimon, for their Nasi sinned [with Kozbi]. It is not said about Binyamin, due to the episode of Pilegesh b'Giv'ah.
Hadar Zekenim (4): Kalev was greatly esteemed. [It was known that] he did not lose his title Nasi (13:2) from when the Meraglim were sent. It does not say Nasi about Shimon, for they did not get their own portion; they were amidst Yehudah. Elidad was Eldad, a Navi, and Kemu'el was Meidad 4 ; they merited to become Nesi'im because they did not want to be aggrandized among the 70 Zekenim (refer to 11:26:2:1).
The nine and a half Shevatim in Eretz Yisrael proper sent 10 Nesi'im to confront the Shevatim in Ever ha