There may be several factors going into this; for example, in the Bay Area, positions in the city of SF are prohibited from considering conviction history that is not "directly related" to the job. It also suggests specific language for including this information on job postings and corporate websites.
I would love to hear from company founders about what factors they use to discover this information in their external job listings that are not on jurisdictions like this.
Source: http://www.millerlawgroup.com/publications/alerts/San-Franci...