I've worked with experts from around the world. After a certain level of competitiveness they are all pretty much the same. Once you become "pals" they all start suggesting improvements. Maybe you socialize better with americans.

Sure, at the highest levels you'll find these traits everywhere. But there is a reason these folks have ascended to the highest levels. What I'm saying is that you find it far more often in junior people in the USA.

I gif it far more often in UK juniors, US juniors tend to be more concerned with moving to their next job than doing the current one.

Maybe we just have different cultural expectations.

US juniors are getting paid a lot more at their second job.

No, you found it in your self-selecting experience.