This argument is quite surface level. For one military uniforms have changed considerably, even since the USA was founded. Are they less military because the uniforms were more colorful.Perhaps one answer is starfleet is more like a coast guard. They have many missions, even have real weapons, with a chain of command and promotion potential.
Starfleet (in my mind) is not a pure military organization. I've served in the USA military over 30 years so I know a little bit. If starfleet were military they'd carry marines (note the show Enterprise) but we don't see them again right? Starfleet's 'army' would wear fatigues instead of colorful sweaters, and their ships would be bristling with weapons instead of science gear.
Two, military isn't just behaviors but legal authority. It's a very important distinction because militaries need legal authority to act on their government's behalf to enforce foreign policy.
As others have noted Starfleet Marines are referenced. But, even if they were not, the actions and authority of Starfleet as presented on screen shows a military organization.
Yeah, that was quite confusing.Also, you said that Starfleet isn't a "pure" military...well, what does that even mean?![]()