system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: does the saying of "communism works in theory but not in practice" have any truth to it? Why or why not?
gpt
The fundamental flaw in communism is that it requires everyone share the same interests and the same opinion on how to serve those interests.  This makes it a very tempting policy position since we like to believe that our own interests and opinions should be universally adopted.

In reality, this situation doesn't occur.  Even when people do share interests, they differ about how best to pursue those interests.  As a result, any attempt to create a 'communist' society inevitably leads to one where a powerful individual or group needs to impose its interests and opinions on the remainder.