Earlier quoted context omitted.
I come from the UK, which is pretty strongly stratified in terms of class (to my knowledge, the most stratified, at least historically). My observation was that, as long as you're straightforward and pleasant, people from all backgrounds are unlikely to dislike you if you come from a 'higher' social class. They'll have lots of ideas about who you are or what you're like, but they are mostly positive. People from rich…
The point is not whether or not the differences are meaningful, the point is the differences exist, and are reinforced by self-selection, conscious or not. Parallel culture if you will. You are right, it doesn't have to be hard to cross the boundaries, but that doesn't mean they don't exist.
My point is the differences are backwards. People think that they're disliked by others, but they're actually projecting their own dislike of others. This happens in hierarchical societies because the people at the top necessarily owe their position to the suppression of the people at the bottom, but since they like to think of themselves as nice fellows, they tend to push all of the emotions this entails onto the people they mistreat. So behind many of these stories of boundaries, there's usually somebody from a wealthy background acting like an asshole to some poor sod, all the while thinking they're just struggling with cultural differences.