I agree on the premise, but Subaru is well known for being behind the times in this kind of technology. Their interiors are really plain and boring, so this is kind of an extreme example.
Still, it's true. I already have a device in my pocket that's far superior than any vehicle navigation out there. At most it costs me $700 for a bleeding edge device at full price. These auto companies want $2-3k for the option when it's a much slower technology. Not only that, but I think they all also charge you for map updates. So while my phone will pretty much always be up to date via Google, you have to shell out an extra $100 per map update to stay current in your car.
I'm actually impressed with how Jeep/Chrysler handles this. I got the larger screen that's "nav ready", meaning I could pay extra to enable navigation at any time, but I didn't have to pay for it just to get the bigger screen. Most vehicles I've seen rope them all together, so if you want the big screen you're paying for the nav system too.