The unfair thing isn’t that it’s not written down though. It’s that it’s implicitly “wear whatever you want, except don’t look like old fashioned corporate America” but claims to be “wear whatever”.

Like the other poster mentioned about hardware vendors at Apple wearing suits, it’s probably not personal it’s just stereotypes at play. Google has a particular penchant for “watch out for tailgating” and expects all employees to challenge folks without badges. It’s not common to see other Google engineers in anything particularly formal, so it becomes a clear “hmm, I should make sure that person has a badge” or alternatively “hey security person, I don’t think they have a badge”.

You've definitely had this shift from chinos/button-down shirts/boat shoes business casual (i.e. more or less traditional East Coast preppy) to jeans/hoodies/t-shirts/sneakers among much of the tech set at least outside of settings like meeting with customers.

I used to pretty much always wear the business casual "uniform" but a few years ago I found myself going a bit more casual at the more developer-oriented events I would attend because I was starting to feel overdressed.

I think that's human culture, not tech culture. Skaters and musicians and preppies and punks and goths and snowboarders and devout religious groups all have their own norms and behavioral and clothing signaling and most of it is not written down.

If I showed up to a half-pipe in full wedding garb or to a wedding in skater garb, people would reasonably give me weird looks.

Being able to appropriately adapt to different situations is a needed life skill. “In matters of principle, stand like a rock; in matters of taste, swim with the current.” —Thomas Jefferson

The benefit I see in tech is you can wear whatever “weird” clothes you want and be accepted and given a chance to prove you can do the job much more than in most workplaces. Try showing up to a law firm or investment bank in flip flops and shorts vs showing up in a suit in tech. You’ll get a lot farther in the latter than the former. To me, that's fair (or at least wildly more fair.)

Maybe I’m an outlier, but I actually like the unwritten rules better than the written ones. Every interview I’ve ever had I make a point to ask what would be expected. At my MBA program (yes, I’m one of those guys) we had to wear slacks and a button down to class every day. And having worked for NYC firms there are different social expectations. So my question is usually phrased like this: “Hey, I’ve worked in situations where a tie was required and where a tie would get one ostracized. Can you give me a quick heads up on normal office attire?”

This usual ends up with some decent back and forth and inevitably I send them the following Oatmeal comic. [0]

My point is that if you play it right, you can turn awkward social norms to your advantage. You just have to be willing to ask.

[0] https://theoatmeal.com/pl/minor_differences5/suit