The larger the military you have, the more expensive to the taxpayer. Assuming I didn't miss some change between the U.S. and Atlasia, Atlasia has nukes, cruise missiles, and tanks. You don't need many people to operate those and we shouldn't be needing to use those much either.
That's a strongly inaccurate view of the military. Sure, we have advanced technology, but we still need strong manpower if we are going to be an active presence around the world. People can do things powerful weapons never will be able to.