That's like the least noteworthy aspect of German anti-piracy action out there tbh.

There's an entire industry around identifying people who torrent and fining them 4 digit amounts as well as forcing them to sign a declaration never to pirate again in their lifetime (which, when broken, results in contractual fines a magnitude larger). Don't want to sign? Tough luck, have fun losing a lawsuit forcing you to sign it.

Not only is it voluntary (can confirm that 1&1 doesn't block the subset of sites I just now tried out which are on the list) but Germany's approach seems to be pretty tame in comparison, still. Doesn't make it good, but a lot less bad than it seems by just reading the highlighted section.

While the CUII website lists 24 platforms for blocking, at last count the exposed list contained well over ten times more domains/subdomains, over 300 in total. For perspective, Germany’s site-blocking program is very modest when compared to schemes in the UK, France, Italy, and Spain, for example, where thousands of sites are blocked with information on domains mostly restricted.

ISPs on a voluntary basis, not the nation

It is but censoring the internet in the name of copyright is almost traditional.