Board Thread:Versus Debates/@comment-26636534-20170822151908/@comment-25122992-20170823170639

Itachi didn't train with Obito, nor did he stayed by his side long enough to figure out Kamui's mechanics completely like Konan. Even if he know about Kamui's existence, it seems that he didn't have enough intel on how it could be used. Otherwise, Itachi would've realised that his Amaterasu trap for Obito was useless and would've prepared something else instead.