For me, it's dependent on how recently I've interacted with the person, digitally or F2F. No niceties at all in replies, "Hey, just to follow up" or the like if we've spoken this week, full formality if it's been a month or more. Civility matters, but shouldn't be its own job.

I agree, but my boss doesn't. She insists on niceties, otherwise she won't answer. ::sigh::

One company I worked at practically wrote me up for not starting my emails with "Happy Monday - hope your day is going great" before "can you please send me that PDF". I routinely wrote the email then went back to the top to add chit chatty opening

I feel this but offer a Counterpoint: what does it cost to make sure your request doesn't come off as a curt command? Some keystrokes, even if it comes off as a little corny?