As for me, White Collar is not a correct translation of Safaid Posh.
White collar person is usually a working and economically active person, while a Safaid Posh could be a person who is no more economically active like a retired person or any other person who has some source of meager income while sitting at home and is able to fulfill his bare minimum needs.
Sadaid posh is honest person having low level of income but fulfilling his needs without asking help from others. He may be working as a white collar or not working at all.