[int_19h]

There's plenty of accidental patterns in purely random stuff. So the thing that the pattern corresponds to, according to your brain, isn't really there - but the pattern itself can very well be.

You know how trees sometimes look like they have faces, for example? They objectively do, according to our pattern recognition algorithm for faces, in a sense that people will find the same tree more or less anthropomorphic. But it doesn't mean that they actually have faces, of course! If you have a still photo of the forest, and stare at it long enough, you might notice more such than you would if you just glanced at it briefly. Same thing here.

[IIAOPSW]

Trees are not accidental. They very much have a pattern. Namely they are in the shape of a tree.

TV static is pure randomness. Looking at any pixel has no correlation with looking at any other pixel. Any pattern you see in static must therefore be an artifact of the way your brain encodes patterns rather than something that is actually there.

[int_19h]

Trees with faces are accidental. Trees don't have faces. They do have various unrelated features, which sometimes combine to form something that objectively looks like a face to humans.

For a more abstract example, if you generate a random black-and-white static image, it will have a bunch of (short) vertical and horizontal lines in it, simply because random pixel values will sometimes cluster into sequences that produce lines. Such a line is "actually there" - different people will see it, and you can even write code that finds all such lines. The fact that its pixels were formed randomly, without correlation between each other, doesn't change this - it just means that the line has no meaning; it's data, not information. But even so, your ability to detect such lines in a static image can vary.

In a similar vein, there's a well-known issue with RNG in games, where a straightforward approach can sometimes result in e.g. repeating the same value in a row many times, which the players immediately notice (and perceive as unfair). Which is why in many games, the RNG is specifically tweaked to keep track of recent outputs and actively avoid producing more output that would form an easily recognizable pattern.