I think what chatokun is talking about is that some people don’t hear their own voice in the way that you describe. I think I am similar to you, in that my thoughts often form a clear, internal dialogue, but I know people who just don’t. It baffles me, because I can’t imagine what the inside of their head must sound like.
On the flip side, I am fairly sure that I have aphantasia (lack of ability to visualise), so often people get confused at this in a similar way. If you’ve never had a thing and don’t really understand what it feels like, it’s hard to understand what you’re apparently missing