At least in Germany there are strict rules for what is called a pretence of self-employment. A freelancer needs to have more than one client, the client cannot

At least in Germany there are strict rules for what is called a pretence of self-employment. A freelancer needs to have more than one client, the client cannot set working hours, access to systems also cannot be the same as for employees etc. US has something similar AFAIK, I would expect most EU countries to have it too.