So not only it is just a plot device with no basis in reality, but even in universe, they don't work.
1. A robot may not injure a tree, or through inaction, allow a tree to come to harm.
2. A robot must obey orders given by trees. Fortunately, this is trivial, as trees cannot speak.
3. A robot must protect its own existence by building a treehouse and hiding in it.
The house would be made of people.
It being a joke is a safety measure. As long as the top comment on every GPT post is someone trivially breaking it and everyone laughing, it's much less likely to get put in charge of anything important. If it wasn't so amusing to do so, people might stop trying, and give the developers enough false confidence to do something actually dangerous.
(And more optimistically, maybe we'll have another AI winter at some point, and we can all get back to doing other things.)