Sure fascism is hard to define not only because in modern usage it has particular connotations aside from what it was: a reactionary ideology that popped up in 1920's - 1940's Italy and adopted in part with a particular racial dimension on top in Nazi Germany.
Incoherent as it was as an ideology it did have particular traits such as being anti-democratic, rejecting democracy in favour of a top-down authority, bellicosity in foreign affairs, and a nationalism obsessed with preserving a "True" culture.
Now sure, the Provists could be described as trying to seek a fascist Caldari State but they would not have come into power and had the support they did have if the threads of authoritarianism, nationalism, rejection of democratic/liberal politics, and militarism weren't already present in Caldari society and the Megacorps.
And that's the thing, the very things that the corporate leadership use to legitimize and ensure their authority as a whole, are also the very same things that can bite them back in the ass when their methods of control fail in keeping the proletariat in line.
Sure, but the Federals, as it turned out at a certain period, also had a fascist bone in their body politic-- and theirs came to the fore much earlier. And I'd argue that due to the decentralized and rather fractious nature of Caldari governance, it's actually the Federation that has a higher likelihood of an abrupt surge of populist sentiment sweeping a fascist figure into power.
The Caldari tend to be relatively trusting of authority and elitist, rather than populist, in their cultural instincts. It takes a pretty major social breakdown for them to lift a Hitler analogue into power, and that's something that doesn't seem to come to them easily (we know of only the once).
Let me be clear: when I criticize the playing of reheated Helghast, what I'm criticizing is the decision to play an unambiguous space Nazi (exactly what the Helghast are in Killzone I, II, and III; I can't speak to the latest), while, I might add, expressing contempt for multiple ingredients in Caldari roleplay that have a pedigree going back WAY before Tony G's Space Hitler-- and before Source. Those more recent sources are canon, fine, but so is Cold Wind, so are the Achura, so's the Caldari sense of honor, and so is the upper crust of Caldari society that did indeed at one time seem to have read way the hell too much Ayn Rand. (Who the hell do you think the revolt that swept Heth into power was revolting
against?! Bunch of Gallentean-inspired corporate types deciding to go all individualist in a society that demands everybody work towards the common good.)
If we need to resurrect the term "fascist" from its moribund status as an insult based on the ways it manifested in the mid-20th Century, fine, but you should be aware that we're now using it in a way that could apply to many authoritarian regimes both before that time and since.
The Rook is absolutely correct that The State is a fictional construct influenced by multiple sources. I'm perfectly happy to concede that there are fascist, and even Nazi, overtones (sometimes quiet, as in Caldari ship design, sometimes overt, as in Space Hitler), but there have been many, many others as well.
To my eye, the worst thing about a fictional fascist entity is simply this: it's boring as hell. Banal as paperwork and dull as dust. The fascist aspects of the State are the ones I'm least-interested in exploring. The interesting bits are in the nuances-- the ways the State functions, and has functioned, as a coherent theoretical entity. Not what makes the Caldari like the Helghast, but what makes them different in ways that matter.
I've always maintained that Eve is a setting short on both heroes and villains. Turning the Caldari into the goddamn Nazis makes for pretty unambiguous, and stupid, villains-- and that sells the whole civilization horribly short. They're both more sophisticated, and more interesting, than that, and while I admire Tom Horn and DK's willingness to go that route, I'm not even a little bit interested in following.