Excellent infrastructure, politically and socially stable, wealthy and with a government that takes an active role in fostering business growth. There's lots of tech companies there although they're mostly focussed on electronics traditionally.
From http://www.state.gov/r/pa/ei/bgn/2798.htm
"Singapore was faced with a lack of physical resources and a small domestic market. In response, the Singapore Government adopted a pro-business, pro-foreign investment, export-oriented economic policy framework, combined with state-directed investments in strategic government-owned corporations."
They're a small country with negligible natural resources but their government has made lots of big bets over the years which have generally paid off. Investing really heavily in education. Actively going after the shipping industry (Singapore is now the busiest port in the world) and a few other industries they see as being big in the future. "state-directed investments in strategic government-owned corporations" is the key phrase in that quote. I sometimes get the feeling they run the place like an enormous government backed VC fund.
My guess is that the Singapore government has an active hand in this as part of a broader effort to build the tech industry in Singapore. Having a government around who is willing to get involved and bet big on the future would be appealing for a company like Amazon.
Yes, those are all good reasons, and as a delighted reader of "The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger" (http://www.amazon.com/Box-Shipping-Container-Smaller-Economy... Highly Recommended!) I knew about their leading role as a container port although not that they're now the biggest.
What I'm sort of musing about is why Japan wasn't chosen. If this were the '80s it would be much more likely, but compared to then Japan is now less politically and socially stable, it's been mired in what is now it's second Lost Decade, the government's "active role in fostering business growth" is gone or incompetent at doing that per se and between the economics and demographics I don't know of anyone who I respect who thinks it has a future.
And I suspect the economic center of gravity of east Asia has moved away from Japan and likely in Singapore's direction. Singapore has of course been hit by the Great Recession, but not (as of yet) catastrophically so, so they're suitably hungry.
If the guess that both of us have made that the Singapore government had a hand in this is correct, it's obviously easier to deal with a small city state than a much larger nation.
