Why don't big patent agencies accept undisclosed business?

Private business is unreliable. Open business means that the supervision work should be carried out in a certain logical order, with words to arrange and guide. The division of responsibilities of undisclosed business is not clear enough and the system is incomplete, which is very prone to unclear division of labor and technical failure, which is not conducive to patent agencies to carry out business, so large patent agencies do not accept undisclosed business.