Question: What do you think are the reasons why some people pick up lost things and don't give them back?
Analysis

This question discusses why some people pick up lost items but do not return them. When answering, you can analyze from aspects of psychological motivation, moral concepts, environmental influences, and personal needs. You can discuss the temptation of personal interests, ignorance or misunderstanding of the return process, lack of legal or social responsibility, as well as differences in moral and values.

Synonyms
Try these synonyms instead of repeating the question:
  1. pick up lost thingsfind lost items
  2. don't give them backfail to return them