In my job description as a Pharmacy Assistant it is required that I take ID Photos whether they be for licences, passports or other forms of identification.
I tell the person when I am going to take it so that they are ready. If the person blinks, I simply take another one as identification in Australia requires the colour of the eyes to be visible.
The part about not smiling is to ease identification purposes. The aim is to have a natural composure on your face. In Canada it is actually legislation that requires passport photos to have no emotional expression. In Australia, as far as I know it is simply regulation.
If you do normally wear glasses, then it is a requirement for your photograph in Australia that you wear your glasses. Just because the flash of the camera bounces off them is not a reason to exclude them from the photo. The camera simply needs to be adjusted accordingly. I don't even have the privilege of working a digital camera, so I have to get it right the first time.
Though there are people out there who just shouldn't take ID photographs. I've told one particular woman how to do her job correctly and told her to re-take the photo. I wasn't ready and I was sure that I blinked and I was not going to have that on my driver's licence as an ID photo. It was all digital so when the manager came out to see what was the matter, it was plain to see that I was correct. There wasn't even ayone else in the post office at the time.