I work in the UK but have studied in Italy.
When I was a student, I'd shoot an email and ask for an appointment to talk about XYZ. At worst, I was told that it was not possible, but it happened rarely.
Now that I'm sitting at the other side of the desk, I'd only expect students attending my courses to show up during office hours, but I'm also happy to see those who would like to talk more generally about academic topics relevant in my field (economics). Office hours do take quite a bit of my time, so I never complain if only a few students show up (or none at all). When overcrowded, I give priority to those students who informed me in advance and/or have more relevant questions about the courses I'm currently teaching.
My own strategy is to publish my office hours on the course webpage (only visible to enrolled students), setting different times and/or days for different courses (when feasible with other duties). For everyone else, I ask them to request an appointment by email. So, were you coming to see me, you'd probably fall in this last category and I'd be happy to see you as time allows.
My colleagues have similar arrangements.
I've had a few students who knocked on my door to ask "What's up with economics these days?" without showing that they did some independent Googling beforehand. While I'd politely answer, I don't find that particularly enjoyable. I'd much rather see and talk to students who show up to say "I've seen [this] and [that] are on these days, but I think [this different but related thing] is more interesting, what do you think?" or "I'm interested in [this problem] but I'm having troubles {starting, finding literature, thinking formally, understanding this paper}."
In conclusion, I'd say that office-hour culture in Europe is indeed different than the American one, although I've never experienced the latter myself and I've only heard from friends about it. But if you wrote to me with a set of clear questions in mind (they need not be formally clear, they only should be motivated by some goal), I'd be more than happy to schedule an appointment. I'd expect colleagues in any other discipline to do the same (but YMMV).