Why do companies need photos with a white background when recruiting?

Photos on a white background apply for social security cards (citizen cards) for employees.

Citizen card refers to an integrated circuit card authorized by the government to be issued to citizens for handling personal social affairs and enjoying public services.

Citizen card has the basic functions of information storage, information inquiry and transaction payment. Citizen card account is a stored-value consumption account with citizen card (or social security card) as the main carrier, which is suitable for the distribution and management of special welfare and subsidy funds for specific people; At the same time, it is also suitable for designated commercial consumption fields. You can set a personal password, register and report the loss, but you can't withdraw cash.