Really? Fucking really?
"This role starts out with a one-week, unpaid trial to gauge work speed and compatibility"

https://www.python.org/jobs/4433/

I guess the finance authority ("Finanzamt") would be interested because that could fall under withdrawal of tax and social insurance contribution that the employer would have to pay for paid work. An e-mail to the finance authority to tip them off doesn't cost a thing and could bring a lot of fun to that company. :-)

Find them, mete out the punishment they deserve.

This is an appropriate response
https://m.youtube.com/watch/...

Thank them for being upfront about their swindling.

Company is based in Colorado, guess it's legal there!