What a stupid move. Has amazon not heard of piracy?
They very well know about it and do anticipate the same but its not always as simple as it looks.
Serving across geographies means having the ability to serve the content to all those requests.
Which is main big problem. (Although for a company like Amazon it is relatively small)
Then there are other issues like local broadcasting laws or content editing for specific geographies. and getting them approved from concerned bodies.
Maybe thats the reason they are holding on for a couple of weeks before making it globally available.
Also what if the response is not how they expected? Although all 3 are major stars and have a huge fan following due to Top Gear the format of TGT is different from top gear and its important it is well accepted everywhere. Thats why they might be planning to scale step by step.