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. So I believe you may take outside food to the theater. Go 90 minutes without eating.
Many people do so every week in church.
My husband and I will soon put our house on the market. It is a beautiful house in a great neighborhood, but the builder cut some corners on the construction . . . My husband says to let the buyer's engineer determine what needs to be done, but I'm afraid he'll miss some things. I said that the seller should answer all questions honestly and should not conceal any flaws but that he need not volunteer every defect in the house. Common practice makes it the buyer's responsibility to have a good engineer check out the place.