I am guessing from your comment that you are based in the US. Welcome to the same experience many of us we have in the rest of the world. E.g. only a limited selection on Netflix, lots of products get released later than in the US, or you go shopping on Amazon and during checkout you are told that some of the items are not shipped to your country.
That being said, there are valid reasons for delaying or avoiding roll-out to some regions. There may be regulations or legal risks which makes the market unattractive, where e.g. US patent trolling could come into play. There are country or market specific requirements or certifications, with agreements, documentation, business support systems, etc which need to be set up to go with that - per each individual market or set of requirements.
With US normally being the first market targeted (huge market, single set of requirements), my guess would be a decision not to go there would have to do with patents or legal risks, not wanting to be pwned by one of the big players.