Seth Stevenson explores them:
Perhaps the most emotional issue in the world of queuing is the human quest for fairness. "When we see people arrive after us and get served before us we get very angry," says [MIT professor Dick] Larson. "We can remember it for days, sometimes. And there have been incidents of ‘queue rage.’ People have drawn knives and guns."
Sometimes we will make exceptions. We seem to be OK with the idea of an express lane at the supermarket—someone buying one roll of paper towels shouldn’t be forced to wait behind someone buying a full cart of groceries. We also allow for differing priorities at an ER, with more critical cases being admitted first even if they showed up last. But in most situations, we demand social fairness. No one is more important than anyone else, and everyone should be served in the order he or she arrived.