There are different ways of looking at a church service. “Gathering of believers” is one, and that doesn’t necessarily correlate with distinctive clothing. “Ceremony” is a different view, and that does imply a “uniform,” whether it’s “military ceremony,” “graduation ceremony,” or “Scouting ceremony.”
Faculty robes at a college commencement are floofy beyond all but the most ancient Catholic or Orthodox Church liturgies, although not as bejeweled as the latter. Did you know that the official color for Engineering graduates is hunter-safety orange?
A gathering of believers is what I think. I stated that I had attended a few brush arbor services as a kid. No one dressed up for those in hot MS in July/August. We used common sense. I did a little research on the Catholic clothes. Every site I went to said that was from left over pagan rituals. I read Ex. 28:2 about the clothes made. But, Jesus did not dress that way.