It's fine in general, but it can't really apply here. This is some people imagining a difference that doesn't exist and then enforcing it on other people whose identities are unknown. Social class has no role to play in the process, except that this is the same behavior that, in other contexts, hardens class boundaries.

In other words, my analysis would be that people are motivated to engage in this behavior without knowing why, and the ultimate reason is to enforce class boundaries, but here they're just going with their instincts even though there isn't a class boundary to enforce.