They could be yelling because they are in a competition or trying to get someone's attention. Sometimes, it's just a way for them to express their emotions freely.
The bellhop could have been yelling because he was caught up in the intense and confusing situation, trying to make sense of it or get someone's attention.
Perhaps the old man yelling in the cartoon is a symbol of protest or a way to express dissatisfaction. It might have a deeper message or just be for comedic effect.
Women yelling in cartoons might be used to emphasize a character's emotion or to drive the plot forward. Maybe it's to show their frustration or to catch the viewer's attention.