>Roughly 4% of the population are said to have aphantasia (lacking a "mind's eye"). Around 10% (numbers vary) don't have an internal monologue.

You don't need either of those to have a world model. A world model is a representation of reality that you can use and manipulate to simulate or predict the outcome of your actions. If you are able to discriminate that one of the actions of accepting a $ 1000000 unconditional gift is better than moving in front of a moving train you have a world model.

You can question the sophistication of world models in people — that's essentially what intelligence represents — but not their existence.