The point of the whatabout tactic is that there’s always something to critique. You can never have a perfect society.
The story about Germany is very different which is they are expressing a concrete concern about a specific situation, not trying to equate one situation to other unrelated situations. There’s also the fact that the UK and Germany are largely allies with similar principles of government and human rights. And of course UK can talk about human rights if it’s explaining how it’s improving it’s prisons or talking about human rights unrelated to prisons.
None of this is true for Russia and China which equate trying to prosecute potentially illegal behavior on the part of Assange (potentially as a Russian asset) to jailing people who expose embarrassing secrets for members of the government or report information not favorable to the government’s perspective. The closest the US comes to that in recent memory that I can think of is what happened with Valarie Plame and her husband (although neither was a journalist nor did they go to jail).