Any stewardess can issue any arbitrary rule and enforce compliance without due process.
Break their rule, and you risk jail, financial ruin, and a lifetime travel ban.
But can’t the flight Captain overrule the stewardess?
And the witches on South West know it. I will probably be banned for my repeated calls to SWA Customer Service complaining about the Gestapo Flight Attendants. I always have a first name, flight number and some description of the evil attendant.
They listen and always tell me it is for the passenger “safety”