A SEO expert who I read regularly thinks the Google Jobs results are being driven by sites that employ a certain job level schema.
He’s probably right. Google needs job data in a specific format and sites that use it are in a better position to be ranked. In the post he points out two examples from Glassdoor and Catholicjobs.com that employ it in their underlying code.
View the schema here: http://schema.org/JobPosting – platforms like Jobboard.io have been using this schema for years. I don’t know if other job board software vendors use it but if not, they better start. If you have a custom built site have your developer restructure the code to comply with these guidelines.