Earlier quoted context omitted.
I‘ve gone through a ton of comments below and see a lot of contradicting evidence to your thoughtful suggestion. Also my girlfriend and I are both from north Europe and I notice a similar difference. Maybe the difference is mostly > she had been brought up to feel extreme insecurity This reminds me of a quote from Buffett from about 40 years ago. He said something along the lines of "when women are raised, they hear…
I generally agree. A lot of contradictory statements and I would only add to that. I feel like people tend to pigeonhole each region in the US, the US itself, and indeed any other country into what “people act like”. There might be a common thread that is statistical but it’s not monolithic in any sense. Micro cultures exist and interplay with the macro culture especially in a networked world.
All this seems like good old stereotyping to me. It often comes down to the individual family or even the individual person. Maybe their social skills, maybe their level of selfishness. Maybe also how much they care about how they're seen by others vs how comfortable they are being themselves. A lot of factors can play into this.