The poem sets two groups against each other: merchants who are loud and comfortable, and "we the people" who have no voice at all. The merchants "bark," a word that suggests both a market seller shouting his wares and a dog snapping orders. They "took no dole," meaning they needed no handouts, and they were "not knowing any want." Their security seems to be exactly what makes them so sure of themselves.
The speaker's side is the opposite. "All throat" is a striking image: the people are made entirely of the part of the body that makes sound, yet nothing comes out. They are full of things to say and unable to say them, as if the voice is stuck or blocked.
The mood is tense and bitter, with a quiet anger underneath. The title, "One-sided," sums it up: one side talks and the other swallows its words. The poem's brevity makes the silence feel even heavier.