Are European Med schools actually that bad for residency?

I've seen on here several times how going to med school in europe is the equivalent of going in the caribbean when it comes to practicing medicine in the U.S. I have trouble fully buying this as both my parents went to med schools in eastern europe. One did a derm residency at a US top 10 school and the other obgyn residency at a decent US school and are practicing here. They genuinely didn't have a problem doing it back then, but according to forums, it appears it's about 100 times harder... Are European Med schools actually that bad for residency?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums