What is up with Facebook and US-only products? Their Camera app is not available in most countries. Even their app for managing Pages isn't available in my app store (they still keep showing me the annoying message to download it). And it takes them literally order of magnitude of months (if ever) to get their products worldwide, like with Facebook check-ins.
Terms of use have to be drafted and reviewed by lawyers for each country. This will take time. Why go through all that trouble and wait months if you can gain valuable insights by a quick launch in your most importanht market?
(And then proceed to put up huge banners in the other apps hassling users to download the new facebook camera and pages apps - even going so far as to provide a button that sends you an international SMS with a link that doesn't even work)
Very few countries have internationalization as a necessity. For most places, having the app in native language is a plus, but most people still frequently use the web in English.
I mean, Instagram could figure all the rollout challenges with a single digit amount of people. One would expect a post-IPO company to do so too.