I mean, there are social codes in any group. It's not unique to rich people, it's just how humans are. There are middle class equivalents to some of these. Growing up, we didn't shop at Nordstrom, but we certainly didn't shop at Goodwill. In most places, there are "middle class" grocery stores and clothing shops. It's just that, if you don't shift groups, you usually don't notice the rules and structures because you've internalized them so much. "What the hell is water?"[1] and all that.