Good analogy, but it is not nearly as close. Movie aspect ratios are actually variable. Most movies today switch several times over the course of the movies depending on what the director wants to convey. The problem is that they can easily do that on theaters, where the screens seamlessly accommodate the different aspect ratios almost imperceptibly for the audience, but to great emotional impact. However, the same is not true for home TVs, it is a little less flexible and far more noticeable.