system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes burner/trap phones untraceable by the police?
gpt
The phone is easy to trace, the person using the phone is not. 

There is nothing magical about the phones specifically, it's how they are used. Burner phones are bought by companies in huge batches, and don't require any plan or contract to use. So there's not a great way to know who is using that particular phone. They are also cheap enough to throw away and "burn" every so often to keep a pattern of use from being determined. 

Even if you could narrow down the phone was purchased at Walmart on a certain date, there wouldn't be a great way to know which one of the hundred that were sold that day is your suspect.