Final answer:
The phrase referring to people who are in close proximity but do not interact with one another is 'casual crowd'. This term is distinguished from other types of crowds which have a more defined purpose or sense of unity.
Step-by-step explanation:
The term that refers to a number of people who happen to be in one particular place but do not interact with one another is called a casual crowd.
Turner and Killian (1993) identified casual crowds as part of the types of crowds, which consist of individuals who are in the same place at the same time but who aren't really interacting with each other. An example of this would be people standing in line at the post office.
The idea is that while these individuals may share physical proximity, they do not have a shared sense of identity or a collective purpose that would otherwise unite them into a more coherent group or gathering with interaction.
Casual crowds differ from other types of crowd gatherings, such as conventional crowds that come together for a scheduled event like a religious service, expressive crowds that gather to express emotions, and acting crowds that focus on a specific goal or action.