The people have enough reasons to hate the Sarkaz, the Sarkaz don't need to give anymore reasons for people to hate them... Perhaps that reason, the Sankta hate them with a murderous passion, the Sarkaz don't need all of Terra to go against them... But then again I've only watched lore videos on Arknights...
I seriously need to play the game already!!! And watch the anime!!!
But yeah those are my guesses...