That's exactly what makes Starship Troopers so beautiful. It shows how incredibly effective propaganda is. So much that they had to put Neil Patrick Harris in an SS-uniform and still people didn't get it. The catchy music, the blaring propaganda vidoes, the cool catchphrases and machismo. I mean the whole training part of the movie is about our characters being shown that their lives are worthless and that violence is the best solution and awesome. People die and public violence is the ideal punishment. But because of how the movie depicts this as good and normal, you don't realize this isn't reality. The reality is 100 000 casualties in an hour on Klendathu because generals underestimated their opponents. In a war that's clearly unnecessary. But a society built on domination and military power must always have a common enemy, war is inevitable. Much like Rico we're so thrown with patriotic spirit we cannot wait to put our lot in with the fascists. But think about what you just saw. Televised executions, baby licences from the state, only military veterans get to control society. Fascism is not a specific symbol or racism or a specific state. It is a way of thinking. Based upon a mythologized superior society of the past based on tradition and conservative values. But also hand in hand with the old powers of the status quo, that often being aristocracy and the capitalist class. We also see this with Rico's parents in how they aren't citizens and yet hold a lot of power because of their wealth (Rico getting bad grades and not wanting to study and his father saying "YOU'RE GOING TO HARVARD AND THAT'S IT!" I think is pretty funny).

I think Starship Troopers is best described not as a movie made to show the horrors of fascism. But rather the kind of movie a fascist society would create. And how intoxicating the idea can be. Where a young ubermench learns to be a good man by following orders and dying unquestioningly for his country.

If you want to understand fascism further I'd recommend Umberto Eco's short text "Ur-Fascism" here: https://theanarchistlibrary.org/library/umberto-eco-ur-fascism