I said it in a previous comment, but they likely arent gullible. This is high society in an era where your standing determines nearly everything. Where everyone wants to be on the winning side but very few are willing to spearhead anything. Its why they mostly just reacted during the temple scene until Ariadne stepped up, its why many made fun of her during the tea party scene until the queen spoke up, and its why they trash talked her with Isabella until Alfonse and later Julia spoke up. They're both capable and willing to think for themselves, thats incredibly obvious, they simply arent willing to voice those thoughts until someone else does because its a gamble: Youre risking your reputation for an opinion and if its not a popular one, then the only one who deals with the fallout is you. Theyre still shi*** people, but I wouldnt consider them lacking in thought.