Yes, for you Brits 40 złoty or 8 pounds sound very cheap, but were not earning so much, the average salary in my city for any job is around 1200 złoty per month for a full time employment, why do you think 2 million Polish people moved to Great Britain?
And your argument that the prices are fine and comparable to other games is simply not true,
sure a slot price is same for another game, but you don't buy a server of 150 slots for those games, those are games have like 64 slots per server.
Most likely the server load will just be the same for other games at 64 slots and this one at 150.. because it will take full on a single core on the server box, so its not like WOR requires more server load than a 64 slot server from another game.
A monopoly is NEVER good. and we can see why. 100 dollar for a server is insane.
Your IL2 argument also doesn't work. I don't know what they are running and how and why, but you can self host that game on a dedicated box, so the prices could be much lower.