I've climbed in Canada, Italy, Germany, and Greece (but not a ton in Italy), and it seems like Greece especially has many climbing areas that are hard to access without a 4wd. I traveled around in a rental and bottomed out so many times, but also had to just give up and turn around on several occasions.

It's been a while since I climbed in Italy, but I remember it being pretty similar.

Admittedly, the limited climbing in Germany I did had pretty good parking access.

I suspect there are many European countries whose climbing access is more like Greece though.

No need to suspect anything. My list included the major climbing areas of Europes major climbing countries and none of them require a four-wheel drive. Even some of the more secluded Swiss areas (Gimmelwald, Rawyl) are easily accessible in a camper van. And I know that for a fact, because I've been there myself.