What China is doing with Hainan - a huge island (50 times the size of Singapore!) - is pretty extraordinary: they're basically making it into a completely different jurisdiction from the rest of the country, and an extremely attractive entry gate for the Chinese market.
You can now import most products in the world (74% of all goods) entirely duty free into Hainan. And, if you transform the product and add 30% value locally, you can then send it to the rest of mainland China completely tariff-free.
So for instance: import Australian beef into Hainan tax free. Slice it and package it for hotpot in Hainan: it can enter all mainland supermarkets duty-free.
They also have insanely low corporate tax rates: 15%, lower than Hong Kong (16.5%) and Singapore (17%) or the rest of the mainland (25%).
That's not all, Hainan now has different rules from the rest of China in dozens of areas:
HEALTH: Basically the rule is that if a medicine or medical device is approved by regulatory agencies anywhere in the world, it can be used in Hainan - even if banned on the mainland. Which undoubtedly makes it THE place in the world with the widest range of medical treatments available.
NO FIREWALL: Companies registered in Hainan can apply for unrestricted global internet access
OPEN EDUCATION: Foreign universities can open campuses without a Chinese partner
VISA-FREE: 86 countries get visa-free entry, probably one of the most open places in the world
CAPITAL: Special accounts let money flow freely to and from overseas - normal mainland forex restrictions don't apply
So they're running a pretty extraordinary "radical openness" experiment there.
They're basically building a "greatest hits" of global free zones: Singapore's tax regime, Switzerland's medical access, Dubai's visa policy - all in one giant tropical island attached to the 1.4 billion people Chinese consumer market.