In message , Cast_Iron
writes
Perhaps it's the obnoxious manner of the questioner that they're
tutting about rather than the simple fact of being asked a question?

Well sadly being asked the same question over and over again even though
the answer is quite obvious to anyone with half a brain cell in a rude
manner and getting no thanks for your answer is part of customer service
and Im sure anyone who works in any kind of customer role (from Tesco
cashiers to the mighty heights of Station Assistant) will tell you they
have to put up with rude arrgorant people.
If you don't like dealing with people. Don't do the job.
--
CJG