Where I live, in the Pacific Northwest, there are company towns, where the entire population of a town works for one company, usually logging companies. They don't have any option to exclude jurors for working for the company the accused also works for (if they're a local). I believe that the reason the jury system works so well is that jurors are indeed zealous to ensure the rights of the accused are respected by the legal process, that the prosecution does effectively prove beyond a shadow of a doubt their guilt, or to conserve the rights of the juror by voting not guilty if the prosecution does not meet that bar. People are indeed zealous of the felicity of their village or town, because their family depends on it, and don't want criminals to prey on themselves, or their friends, family, neighbors because that threatens themselves and their family. Juries are motivated to judge truly and justly because of these factors.