That people with drug possession charges don’t lose their jobs here, even office workers or teachers

Especially those. For criminal things to become relevant they have to be connected to the job at hand. Hence drugs would be mainly an issue in areas where you operate heavy machinery.

Fun fact: You are allowed to lie about your criminal past in job interviews if it's those are not connected to the job. Hence any smart employer will only ask whether you were convicted of anything that is relevant to them. Otherwise firing you will be expensive. And of course it's also hard to employers to find out whether an employee has any criminal convictions. Afaik only a few select areas, e.g. the arms industry and kindergartens (the later look for sex and violence related crimes, not drugs), actually check criminal records and they do have to get permission from you or you'll even have to get the documents ("Führungszeugnis") yourself.