Yes, and no. People who
observe people striking up a conversation are likely to react in that way, but in my experience people who are approached are almost always friendly even in Northern Europe when approached by a stranger.
In a way, striking up a conversation with strangers in Northern Europe is easier than in the US, as nobody expects it. "Everyone" will wait to hear you out. No matter how awkward and nervous you sound, people will tend to lap up the attention, because it is so rare.
I'm quite introvert, and a few years ago I decided that I was isolating myself too much, and decided to make some very basic changes. For starters, I decided to greet people as much as possible, and to aim to get eye contact. Not with every random stranger, but e.g. cashiers in a shop; bus drivers etc. or other situations where there was "natural" contact.
What I didn't expect was the outcome: Within a couple of weeks, the cashiers at the shop I used to buy my lunch in were pouring out their life stories to me, after I'd been going there for months without even recognising any of their faces before. If there was a queue, they'd rush past me and motion me to their till and open it. One of the bus drivers that had been on my route for years without me ever recognising him, approached me when he suddenly recognised me at the gym, and we now chat whenever we see each other.
I've since occasionally chatted up total strangers in the street too, and the worst reaction I've ever had was a single time when a girl just kept walking and told me "not interested".
Frankly, a bar is a far more brutal environment. For anyone that fear rejection that wants to talk to strangers, random passers-by on the street will be far easier than a bar or a club even in Northern Europe.
I think the mindset both in the Nordic countries - I'm Norwegian - and England where I'm now, is that other people will think I'm weird if I talk to them, while at the same time because of that, people see it almost as a compliment if they're approached by people that show a genuine interest in them (e.g. in London my experience is that you'll get a positive response from pretty much any random stranger on the street unless you come across as representing a charity; in England there's a word for people collecting for charities on the street: chugger - a contraction of "charity" and "mugger").