Identify three industries that may have difficulty identifying their end-user customers

Identify three industries that may have difficulty identifying their end-user customers. (Do not take the examples straight from the book.)

1)      Industry 1: What makes identifying customers difficult in this industry? How would the industry approach identifying its end users?

2)      Industry 2: What makes identifying customers difficult in this industry? How would the industry approach identifying its end users?

3)      Industry 3: What makes identifying customers difficult in this industry? How would the industry approach identifying its end users