I would tend to think it's the fine Maps detail on every road in every country that Navigation works in - all of the details of every single intersection, how m

I would tend to think it's the fine Maps detail on every road in every country that Navigation works in - all of the details of every single intersection, how many lanes, what turns you can make from where, etc. The maps and images are expensive, but they already exist and can be bought, if you're willing to pay the price. That detail info doesn't even exist anywhere, at least not in any kind of consistent and reliable way. The only way to get it is to employ a virtual army of drivers to drive every single road in every country, record a ton of info about them all, and figure out how to store it all in a searchable format. And then keep doing it forever, because those roads all change periodically, and often nobody every documents how or where or when.