Companies would much rather miss out on growth than have employees who have any kind of leverage over them.
You're talking about a culture in which the standard greeting is "How are you?", and the standard response to said greeting is, "I'm fine!" - even when you're obviously not fine.
So, no, it's very much not direct. If you want to see what a "direct" software engineering culture looks like, look at Eastern Europe. There, people will routinely say things like "this code is crap", and no-one (including the author of said code!) bats an eye at it because it's supposed to be taken at face value, not as an insult.
You want the shitty PHB megacorps to reject you so you don't win to lose by getting a job you are going to hate.
Only when talking to people beneath them. When talking to your superiors, you should be deferential and circumspect.
American society is more hierarchical than a feudal aristocracy. It's just based on money, skin color, and gender instead of family name.
And bosses who read between my lines? Terrible.
Read some communications book. Reading between the lines and using tact are the (literal) textbook cases of poor communicators.