In some cultures, perhaps. But I assure you, my n=1 experience is with plenty of companies that switched from a typical jacket-and-tie dress code to business causual, and ended up with a “huge amount of variety:”

All of the men wore golf/polo shirts, khakis, and tasseled loafers, but some wore oxblood loafers while others wore black or even brown loafers. And some wore plain leather belts, others wore woven leather belts.

</sarcasm>

Some cultures value conformance, and even if the rule is “wear whatever you like, as long as it’s not jeans or tee shirts,” they’ll self-organize around an unwritten rule of what to wear.

I'm afraid that's more of a reflection of people's taste in clothing where you live than anything else.

We'll have to disagree on this. What you call a bunch of people having the same taste in clothing, I call social signalling.

For n=1 that might be true.

How do you figure that? If there is no dress code, people can wear everything in the set you’re describing, plus the no dress code set.