Not sure I agree with you here. Westeros is totally made up so if I had never seen even a crappy map of it and was watching the show I might not get that King's Landing is near the southernmost tip of their kingdom, or that the Eyre is apparently on the eastern coast, and south of the Iron Isles, which are up near the Wall. As an average viewer I certainly am not going to go looking up a map to figure it out, so I want that presented to me within the show or I'm just going to assume they don't care or want me to know. But they do tell me enough that I don't need another map to at least have a vague sense.
Now, as an average viewer, of The Expanse I might know my Solar System pretty well from elementary school. I might even know Pluto is no longer a planet, RIP, frowney face HashtagPutBackPluto or whatever. I might even be somewhat into my space facts and sci-fi and know that some of the moons like Europa, IO, Titan, and a bunch more are around either Saturn or Jupiter. I might be able to say Ganymede is definitely one of those too.
OK they're on Ceres, that's a moon right? Oh, it's not? Oh, was it the tiny planetoid near Pluto? So they're really far from everything? No, it's in the belt eh? OK cool, A belt moon!
And then now they're on Eros. it's also an asteroid in the belt? OK. Wait it's an asteroid that sometimes is closer to Earth than even Mars? So it's not really a Belter kind of place is it, being down the well from even Mars. Except it looks pretty Belter to me. Guess it's in the belt somewhere for now. But is it anywhere near the other belt stations or is it literally on the other side of the belt? The belt is a big place after-all. Guess it doesn't matter?
That's the kind of confusion that comes up even for me at times, and even some basic Google searches of the Solar System will not yield data sufficient to point out where these various things are unless you start looking up the locations one-by-one. I only just now found out the big where Eros actually sometimes comes in and crosses the Mars orbit down into Earth's. That's an insane fact! That might have huge implications in the story! Knowing that changes things potentially. Especially by the end of season 1 if you know Eros could be near Earth, that's like 'oh shit'
But, OK, occasionally we see a hologram of the system in the show, and sometimes people will drop enough hints to get maybe an idea of where some stuff is. It never really truly hurts the show and you can totally get by only knowing the order of the planets and just go with the rest. And, Syfy put up a pretty cool interactive map on its website that does help a lot with showing where all this stuff is. But again it requires you to go and look it up. The show could spend a few seconds every once in a while and do the same thing right in the primary source.