Comment by amonith
There's a "threat simulation theory" that sort of explains it, but it's not 100% correct for everyone. TL;DR: in dreams your brain often seems to practice "threats"/stressful situations. E.g. you're more likely to dream about missing work, having exams, car breaking, running from someone, interacting with someone you care about etc. rather than doing something you're completely used to.
I wonder if very small children dream about screens then don't understand. Like, if a poor small child got hit with the car commercial or the maze jump scare, would that get added to the threat list? I'm talking young enough that they can't tell you it's a screen. Do babies dream? What could they ever dream about? Is there a library of set concepts that we're all genetically made to fear, if so, how would that be represented in dreams? Gosh