A monkey could do the work. And while civility requires that nearly all of us follow the rules nearly all of the time, it does not mean that we should not think critically for ourselves. There are unworthy rules that you may break without being dishonorable. A valid ethical precept must work not just for one particular case but also for all similar situations. For an agreement to be meaningful, it must be entered into freely by both parties, hardly the case when a theater owner stamps a list of rules on the back of a ticket.
Rules ought to be reasonable.
And there is a difference between the rules imposed only through the authority of private property and the laws devised by a democratic society, which at least strive for the consent of the governed and are nominally under the control of their representatives. The latter have more legitimacy than the former. Commerce, too, should be freely entered into. And if fewer purchases at the concession stand mean a theater has to raise ticket prices, so be it. That is also a part of commerce.