It’s actually British courts who are special. And unfortunately Britain has exported their way into all their colonies.

In the British view of the world, it is generally assumed that everybody is lying all the time, even in court. All evidence and all words of witnesses are assumed to belong to one of the parties = lying in their favor (If you don’t like the term “lying” here, you can replace it by “performing a good show”).

In Germany, witnesses belong to nobody (except if they are are involved, or if they are spouse/relatives to one of the people who are involved etc.) and therefore it is generally assumed that they are free to tell the truth.