Some European PhDs are worthless. Dr. med and Dr. jur (medicine and law) are a joke in Germany. You can obtain a Dr. med after one year of injecting $random_substance into mice and repeating the "experiment" until the p-values spit out by Excel are sufficient for the "thesis" to pass.
Dr.med. and Dr.jur. are not the equivalents of PhD/DPhil, they are the equivalents of MD and JD degrees, which in terms of research output are also a joke in anglo-saxon countries. In the US, medical doctors who wants to pursue medical research usually do a PhD _on top_ of their MD degree.
PhDs in e.g. Physics are harder though.