this question could also be explained using the concept of elasticity. During the day time, there are a lot more activities people can do other than watching a movie, meaning there are more substitutes for movies. Thus the price elasticity of watching a movie is more elastic. However, during night time, the number of substitutes decreases, and thus more people would choose to watch a movie. As a result, the price elasticity of more will become more inelastic during night time.

Therefore, during the day time, it's more elastic, so the price is lower. whereas during the night time, it's more inelastic, so the price is higher.

这纯粹是价格歧视问题，因为白天和晚上的需求不同，所以为了使消费者盈余降到最低（甚至是零）白天和晚上的价格就当然不同了。