Perhaps the countryside was not well maintained by the authorities. Jerusalem was/is a major city under Roman occupation. I repeat, Pax Romana, Roman Peace, known throughout the world and repeated in Western civilian history books since Roman times. It was taught in elementary school. It was the major administrative of Roman occupation. Jerusalem was also a major financial center. Nazareth did not matter much. Jerusalem mattered. Just as Manhattan gets outsized resources b/c of the revenues it generates, Jerusalem would have been a special case.
Also, this incident occurs during the Passover Festival. Countless thousands of villagers would have flocked into Jerusalem. The Romans definitely would have garrisoned more troops than usual. It was clear to the Romans that even a small demonstration could lead to massive riots and a threat to their rule. Furthermore, Jewish authorities would have been in out force. My local priest said Jerusalem was not a world city but during Passover the population exploded.
Now that others has posted, I agree that it is written to fulfill some Old Testament prophecy. Jesus used very violent imagery in his apocalyptic sayings. He brings an ax, there is another sword reference. He comes not to unite but to divide. The sayings of Jesus that seem out of character. The Last Temptation of Christ emphasized these sayings.
Of course, the Hebrew Scriptures were written for Hebrews, not Christians. When Christians mess with the Hebrew Scriptures in the Greek sciptures, it will never come across naturally. I don't think the suffering servant verses from Isaiah apply to the sword and ear incident. It applies to the overall story. Of course, the suffering servant was not Jesus.
I still find the story very humorous. When I was young, I wondered about the ear. Maybe where Jesus says let those who have ears, hear. No matter what prophetic interpretation, the ear slicing is bizarre. Peter really showed them. If you saw an ear amputated with pure rage, after Jesus says to love your enemies, and Jesus healed it, would you still arrest him? I would be awed and prob. convert.