In certain geographic and/or certain academic circles leaving out the 'dr' is, depending on how you look at it, a newish kind of snobbery or a recognition that

In certain geographic and/or certain academic circles leaving out the 'dr' is, depending on how you look at it, a newish kind of snobbery or a recognition that getting the PhD isn't all that much of an accomplishment. Not putting emphasis on the 'dr' part is like saying 'of course everybody who matters has a PhD, no need to mention it every time'. It's the same reasoning as why one wouldn't list a driving license as an accomplishment when one is a professional race car driver - 'of course' everybody who is somebody in racing has passed their driving exam a long time ago. (the same comment was mentioned in the comments to the OP - I was quite surprised nobody mentioned my above reasoning, I thought it was common knowledge by now).