I mean, this is much, much worse in the US with olive oil. As that article points out, the majority of the fraudulent olive oil is sent to the US and Japan. Why? Because the EU has regulations and tracking, and whilst that isn't perfect, it's insanely more than the US does (even before recent... er... setbacks), and more than I assume Japan does re: foreign goods. And the article points out that the real test is in your kitchen - you can tell if it's rubbish, so long as you know what it's supposed to taste like.
The EU in general regulates quite a lot of these claims - albeit not coffee AFAIK because it's not grown here. The biggest scandals here recently have all been around honey, which had (and kind of still has) weaker regulation. I think it's probably easier to reliably get single origin non-adulterated honey in the US right now.
That said it is pretty easy to tell, say, Ethiopian single-origin coffee apart from, like Colombian. Certainly since I got an actual coffee grinder. I know it is because I've forgotten what kind of beans were in the grinder before and then been like "Oh wow this definitely X", then checked the package in the bin and it is (I prefer Ethiopian to other kinds, it's got a lighter to me somehow more coffee-like flavour)