No "Hello", no "Please", Poor english, add to that the fact that nobody knows the answer, so why should we even bother to respond?.
Aah, the eternal question. This has been asked everyday since google even made PR, and of course, no one but google knows the answer.
According to the posts I've seen on this forum it's expected all day, every day, 7 days a week, 12 months of the year - and a lot of people are scared to blink in case they miss it.