That's a manifestation of your specific environment and not a general rule. I guess it is the work of some overeager compliance department, because it is the kind of overreacting self-mutilation that happens if people do not understand a law and want to be absolutely sure (cf. GDPR).
[1] is a PDF that tax advisers and lawyers distribute to employers to check if freelancers are only ostensibly self-employed. The checklist at the end of the PDF is all you need if you are an employer. If you are a freelancer you must also check if you are employee-like and possibly file an application to be exempt. The PDF tells you when. Watch the 5/6 distribution of income (not law, but established judicature)!
[1] is a PDF that tax advisers and lawyers distribute to employers to check if freelancers are only ostensibly self-employed. The checklist at the end of the PDF is all you need if you are an employer. If you are a freelancer you must also check if you are employee-like and possibly file an application to be exempt. The PDF tells you when. Watch the 5/6 distribution of income (not law, but established judicature)!
[1] https://www.sup-kanzlei.de/fileadmin/user_upload/Scheinselbs...