I lived in the Netherlands, England, Ireland, and New Zealand; England and Ireland are not "bike countries" either, but for the most part it was actually pretty okay cycling in the city: there are enough cyclists around, roads are small, and most people understand that the limited space needs to be shared.

New Zealand, however, was a different story. The roads are huge, US-style, and a significant number of cyclists think that the road is for them and them only which, given the design, is not even entirely invalid as such. You get aggressive drivers everywhere (including NL), but the incidence in NZ was far more often than anywhere else. I think the mandatory helmet laws aren't helping either: it instils the impression that you're doing something inherently dangerous on a space not intended for you.

Actually the most careful (car) drivers I've seen was in Indonesia, where roads are for scooters first and cars second.