In modern times, countries with organized armies have assimilated the ranking structure of other countries, mostly due to NATO or the UN Security forces. This is why they look similar. Uniformity allows some respect within the chain of command. You don't want a Lieutenant of one army addressing a General of another as a trash. It's just a matter of making things easier. But it is nevertheless important to always keep in mind that this is a Japanese show and that they use Japanese military ranking. Just like in shows or movies in the USA, they will use the US military ranking system because it is a USA production even if there are international or other-worldly characters.