(Similarly, someone elsethread is talking about how their non-developer colleagues neglected to tell them about an upcoming release. One possible explanation is that their colleagues were bad at "theory of mind", and believed that as they knew about the release, so did everybody else. But I think it's more likely that they were too disorganised to make sure that it was somebody's job to tell everyone who needed to know.)
The "theory of mind" explanation is that those developers don't understand what context other people are probably missing.
I agree that there are of course other possible reasons.
if you get an email from me, and when you want to follow up you're thinking "what was that phone number I should call?", don't worry, I have already put it in the subject line along with the person's name and the deadline
Taking "I need X next Wednesday" at face value to mean "as long as I have X by 5pm Wednesday I'm happy" is completely reasonable.
I remember once seeing the inbox of someone working as a sales-ledger clerk. It was full of messages with the subject "accounts query", or a small variation of that. The ones with subjects like "query for account ACME-37" were from technical staff.
Similarly if I ask "when do you need those figures?" and I get the answer "next Wednesday", it isn't when I'm talking to programmers that I feel the need to follow up with "Is that when you want me to give them to you, or when you're going to be making the presentation that includes them?".