The entire point of using a map is the data. Who cares about the chrome of the app?

Well, for example, I won't use Google Maps for driving directions because of a chrome issue: The voice they use is about the same pitch as the background driving noise in my car, so it can be difficult to understand if I don't really crank the volume.

Apple Maps doesn't always find the fastest route, but at least I can understand what it's saying.

You must mean the UI - although that's debatable, in my experience.

Personally I won't use Apple Maps while driving, for example, because Google Maps lane hints provide a much better experience - although when I was out of the UK recently, I wad disappointed by how poor Google's routing was on some journeys.

But even if it were true - what's the point of a good UI if it displays bad data?

At least in the US when I've used it, Apple's lane guidance is pretty comparable to Google's (i.e., mostly but not always on target).

I suspect "bad data" is both a little subjective and, as I mentioned in another comment, very location dependent. It's quite possible that one of the reasons Apple is starting to build their own location data set is because relying on other providers leads hasn't worked out so well for them outside the US. (Although I suspect they're going to still be dependent on those providers for years to come.)

People don't make a distinction like that, and why would they? The app UX includes functionality, not just visuals.