As China EV blogger Alysha Webb reports, Tesla's explanation for the lack of a nav system is that "Google maps are not supported." At least the company is working on an alternative map database for the land where Google doesn't work right. We've confirmed with Tesla PR in the US that Webb's report contains an official Tesla response, which includes the following:
One interesting quirk is that Tesla can't yet push the updated map to everyone over the air, since, "remote over-the-air software updates are not yet supported in Chinese Model S." Instead, Tesla will have to rely on its backend system to update the EV to what most American customers would consider standard equipment in a car in this price range. You can read the whole thing here.
Currently there isn't a navigation system in Chinese Model S as Google maps are not supported in the country. However, teams are currently working on a solution with Chinese text and voice recognition. We plan to introduce navigation to Chinese cars later this year (as already communicated to our customers). Once it's available, maps will be pushed to customers' vehicles through software updates.