There are so many reasons that Hong Kong provides the ideal situation for Tesla's vehicles.
As pointed out by Teslarati, the ridiculously high vehicle registration fee (as much as 115% of MSRP) is waived for electric vehicle owners. Due to this anomaly, the math will tell you that you can get a Tesla for about the price of other ICE luxury cars. Factor in some of the highest gas prices in the world, and owning a Tesla is much cheaper.
Tesla Model S in Hong Kong
Although Hong Kong is super-populated and developed, it is tiny. Therefore range is not even a consideration, however, there are still conveniently located Superchargers everywhere.
In fact, Hong Kong has the highest density of Superchargers on the planet. This is likely one of the number one reasons that, of the 7,000ish EVs on the road, 4,000 are Teslas. In 2010, there were about 100 registered EVs on the island.
We should note that due to congestion, there is an issue with many Tesla owners not having a "personal" or home space to plug-in, meaning Tesla Supercharging stations and public DC fast charging locations are the only available options to get a boost.
The healthy government incentives will likely fade in the near future, or be reduced, but the cars will still be an economical no-brainer. Hong Kong is reassessing its EV tax in March.
Hong Kong is known for its love of technology, and interest in speed and performance. You can't really find another car company that performs better in these areas than Tesla. Air quality and noise pollution are two substantial considerations among citizens and government on the tiny island. Elon Musk knows full well of Hong Kong's importance to Tesla. He said:
The city is a “beacon city for electric vehicles” to “serve as an example to the rest of the world on what to do.”