[1] To be fair each society has its own expectations on what interpersonal relationships should be like. American openness/directness likely isn't inherently virtuous.
My Thai friends are much more direct discussing appearance, for instance. As an American, that was actually quite a shock visiting Thailand -- but you get used to it and adjust, and now it feels weird that there is this taboo in the US.
Americans are more open and direct than Japan, but I don't know that I'd say they're particularly open and direct -- about the only thing I'd say Americans are uniquely is boisterous. But that's probably still only among the developed world.
I'm not sure how best to describe the difference. When I talk to Japanese "friends", I feel that I am talking to a mask, or that they're playing a part. In the States, on the subjects that we are open with, we seem to want to show our true selves, whatever that may mean. In Japan I feel that every aspect of your communication is guarded.
At least part of his position is true though -- the education system really doesn't cultivate critical thinking or original thought (other than the elite prep schools which are great at fostering individuality).
The most sincere and interesting discussion were late into the night where half the people were sleeping under the table and the few left awake were articulating thoughts they had very deep in heart.
There’s of course the part where everyone is a bit more lubricated, but there’s also the social protection of “being drunk” that helps to shield from repercutions if we step too far on people’s feelings.
I found this specially true for people who are pretty strong to alcohol, and tend to wait for these “end of party” moments to start discussing intimate feelings, even if they are still almost sober.
In the Czech republic people don't talk as much and generally these situations occur rarely. And the example that I gave of the people in the park just doesn't happen in the Czech republic. There is no requirement to invite someone someplace just because you are going there yourself.
That wasn’t the effect you were demonstrating above. It was more “you have to invite [friend A] if you invite [friend B] from the same social group, unless you want [friend A] to think that you value them less than [friend B].”
Which is sometimes obviously what you want them to think—if you have known [friend B] for years and you’ve just joined the group that introduces you to [friend A], then hanging out solely with [friend B] (in a way that [friend A] will find out about, like by inviting them in front of them) is a way to assert that you’d like [friend A] to get to know you better, because you’re still not at the level where you feel comfortable adding them to your more close-knit friend group yet.
The problem comes when you’ve just joined a group and so only know everyone equally well (i.e. not that well), and yet only invite some of the group members somewhere anyway. This reads like the signal above, but without a justification: the people you chose to invite out did nothing to “deserve” the choice, and there’s no obvious thing (like more shared conversation) that you’re signalling that you’d like out of the people you didn’t invite. It can seem like you’re just sociopathically playing members of the group against each-other to win your favour.
But that’s really the only scenario where this applies: when picking a subset of acquaintances, from a shared group, to do something with that is usually reserved for friends. (It does come up a lot, because a “pool of shared acquaintances” describes a school pretty well. But it’s not nearly as much of a “thing” outside of that.)