That's because they're specialist importers. If regular overseas retailers like say Toys R Us, Target, Kmart etc. wanted to release TakaraTOMY TFs, they would refuse. The only way they can do it is to import it through Hasbro. That's how we've had Takara(TOMY) TFs sold in regular Australian stores in the past (e.g. MP Ultra Magnus, MP04, MP Ghost Starscream etc.) - they would have been distributed by Hasbro Australia. Those store chains didn't source them directly from Takara(TOMY). Specialist import stores would, but of course in Australia they get slapped with loads of import taxes, duties, levies etc. which often doubles their original prices when sold here.
Hasbro would sell their stock to specialist importers in Japan too (e.g. Mandarake, Jungle, Hero Gangu etc.), but regular store chains in Japan (e.g. Daimaru, Itoyokado, Bic Camera, Seibu, Tobu, TRU etc.) normally don't sell Hasbro TFs, and if they did it would be distributed by TakaraTOMY. So Hasbro and TakaraTOMY can sell products in each other's markets with permission from the other party -- but they don't develop products with each other's markets in mind, unless it's a dual project where they're developing something in tandem. This is what Takara have explicitly stated. Is there any evidence to the contrary or only speculation?