I'm tempted to think that's an artifact of a tendency in writers to give their characters thought processes resembling their own.

I don't think it's anything especially related to writing; I think everyone does it in their normal life: you want to think about how so and so is going to react to whatever, but the best we can really do is consider them as basically like ourselves +/- some known differences (which for many things is sufficient, but in my experience can also lead to absurdities due to how vastly differently some folks think).