Except where the provisions of this code require the refusal to issue a license, the department may issue a probationary license subject to conditions to be observed by the licensee in the exercise of the privilege granted. The conditions to be attached to the exercise of the privilege shall not appear on the face of the license but shall be such as may, in the judgment of the department, be in the public interest and suitable to the qualifications of the applicant as disclosed by the application and investigation by the department of the information contained therein.