system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a death penalty execution cost more than keeping the person in prison for life?
gpt
It wouldn’t if the execution was immediate. However, most inmates appeal court decisions meaning basically they have to redo the trial. And as long as they can bring new evidence they can keep appealing.  
So you’re imprisoning them which is the same cost as other inmates and adding near endless trials on top of it.