I was going to say that they seem to be everywhere these days but actually I can only think of three recent ones. But three is a lot right?
The junkyard in Becky Chamber’s A Closed and Common Orbit (reviewed here). The book has two interwoven stories one about an AI trying to live as an embodied being with help from her friends and the second story told in flashback about Jane – a cloned child who (along with other cloned children) works in a giant junkyard on an isolated planet.
The San Jose junkyard zone in Blade Runner 2049.
Without spoiling the plot Ryan Gosling visits this hi-tech scrap heap to interview the owner of an orphanage which turns out to be…a child slave labour workshop where kids recycle hi-tech junk. Given the timing of the film and Chamber’s book it is unlikely either cribbed from the other but the visuals in Blade Runner 2049 almost work as visuals for Chamber’s book.
Less focused on the horrors of child exploitation we’ve also had recently the giant intergalactic junkyard from Thor Ragnarok (review here):
Is it just me or do junkyards only exist on cloudy days?
The city in Borne isn’t technically a junkyard but it has similar tropes of gangs of scavangers making use of the remains of technology but with the twist that it is discarded bio-tech. I guess The Phantom Menace has the child-labour-junkyard trope but without the giant space junkyard.
As a piece of plot territory, the giant junkyard is one that is implictly science-fictional rather than fantasy or at least requires a society in which mass manufacture is a thing and hence the disposal of used goods is a thing. A junkyard can then become a place in which the fringes of society live but also a place where technology can be found.
A junkyard is also a place that hides in plain sight. They are by their nature visible but exist where people with wealth can ignore them. There is an in-built critique of capitalism (whether an author intends that or not) with an implication of the ugliness of waste. The inhabitants of the junkyard are also people being discarded by their society – the sfnal junkyard is rarely a day job but instead home to gangs or slaves or slave owning gangs.
There’s an implication of secrets, forgotten knowledge, death and also rebirth in the fictional junkyard – dead things coming back to life for good or ill. An alchemical theme to the junkyard.