The EU doesn't do[0] Common Law (Case Law), like the US does, we have Civil Law here. It means precedence doesn't carry (as much) weight. It's a different legal system. It also means it has been written (codified) into law, unlike your previous comment states. You can read it in the article and links followed from there (it doesn't need to be written to specifically apply to websites).

https://en.wikipedia.org/wiki/Common_law#Alternatives_to_com...

Be sure to also check out the coloured map at the top :)

[0] it's a bit more subtle, distinctions have blurred a little over time, either legal system adopted some parts of the other. see the wikipedia link for more details (especially the heading "Alternatives to Common Law systems")