system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why in dystopic films or tv shows (Walking Dead, The Last Man on Earth) isn't there power or internet available? Unless someone shut's the sources off, wouldn't they still be working until they break down?
gpt
These things aren't self-sustaining.  They require a lot of work to keep working.  Even in a medium company you need an IT department to keep everything from going down constantly.

Power requires fuel, which needs to be managed.  Not everything is automated, so fuel can run out.  Additionally, during an apocalypse people are burning things, running into power poles, fires breaking out, which can also cause the grid to have issues.  There's a lot of load balancing, some automated, some manual.  If no one is around to do the manual part, then it would most likely shut off sectors of the grid to prevent a problem.

Electricity would go for awhile, and cell towers have battery backups that can last awhile too, but none of them are designed to work completely unmonitored and without help.