Of the 30 cabin behaviours YouGov tested, this is the most evenly divided of all: 38% acceptable, 36% unacceptable, a two-point gap. It also carries the largest undecided share on the entire list, at 26%. YouGov singled it out as one of four genuinely contested behaviours, alongside phone calls, small dogs and early unbuckling. The size of that 'not sure' group is the tell. On most items Americans answer instantly (86% say letting children play in the aisle is unacceptable, 81% say using a laptop on the tray table is fine), and the undecided share sits in the teens. Here a quarter of people decline to rule at all. That fits a conflict in which both sides have an obvious claim. The light is fitted above a seat for the use of whoever is sitting in it, and it points down into a row where other people are trying to sleep. Nothing in the cabin says whose turn it is, and the survey suggests most passengers have never decided.