This is in fact the advantage of having a widely-understood dress code for things such as interviews: that way no one has to play guessing games, you just show up as expected and it's one less thing to think about.

Unfortunately, our industry has no such thing, so I always ask before an interview. So far the answer is always "uh, we just wear normal clothes", "casual is fine" or once "just wear clothes, please, this isn't quite Burning Man" (ended up working at the last place), but: this was in the Bay Area, so YMMV.