Final answer:
Nick chooses to wait outside for the taxi because of his discomfort with the tension inside the Buchanan's house.
Step-by-step explanation:
The reason Nick does not wait for the taxi inside the Buchanan's house is because he is uncomfortable with the tension inside the house and prefers to wait for the taxi outside. This discomfort is related to the complex social dynamics and the unease he feels in the presence of Tom and Daisy Buchanan and the general atmosphere of their household. Nick's preference to wait outside indicates his desire for a brief respite from the intense environment within the house and perhaps his own need for a moment of reflection.