I wonder why some people only say what they want to say and then leave

Sometimes, while working at a company,
I frequently encounter people
who come to ask me questions.
Usually, if the other person is busy, they will
ask for understanding and seek permission before asking,
but very occasionally, I encounter people who
just come to my desk, ask their question,
get the necessary answer, and then leave.
(This happens regardless of the person's rank or position)
When I see people like this,
I honestly don't know what kind of upbringing leads them to act this way.