Albert Barnes Commentary Amos 2:3

"and I will cut off the judge from the midst thereof, and will slay all the princes thereof with him, saith Jehovah." — Amos 2:3 (ASV)

And I will cut off the judge – The title “judge” (shophet) is nowhere used absolutely of a king. Holy Scripture speaks in several places of all the judges of the earth (Job 9:24; Psalms 2:10; Psalms 148:11; Proverbs 8:16; Isaiah 40:23). Hosea (Hosea 13:10), under the term “judges,” includes “kings and princes” as ones who judge the people. The word “judge” is always used for one invested with the highest, but not regal, authority, as with all the judges from the death of Joshua to Samuel.

Similarly, it (Sufetes) was the title of the chief magistrates of Carthage, who held much the same authority as the Roman Consuls.

The Phoenician histories, although they would not acknowledge that Nebuchadnezzar conquered Tyre, still acknowledge that after his 13-year siege, Baal reigned for 10 years; and after him, judges were established (one for two months, a second for ten months, a third, who was a high priest, for three months, and two more for six months), and between these periods of judicial rule, one person reigned as king for a year.

After this king’s death, they sent for Merbaal from Babylon, who reigned for four years. On Merbaal's death, they sent for Hiram, his brother, who reigned for twenty years. The judges at that time exercised supreme authority, as the king’s sons had been carried away captive.

Probably, then, when Jeroboam II recovered the old territory of Israel, Moab lost its kings. This aligns with what Amos says, the princes thereof—literally, “her princes” (the princes of Moab)—not, as in the case of Ammon, “his princes” (that is, the princes of the king).