Let me clarify a couple of points:-
We are busy, but not understaffed for the job for which we are paid, namely dealing with Birmingham traffic, i.e. inbounds and outbounds. We are not paid for, therefore not staffed for, extraneous traffic outside the CTA. Whilst we endeavour to assist anyone who calls, we must limit that level of service to allow us to deal with our prime task. (We are, incidentally, staffed to open an extra coordination position at the busiest periods if the prime task requires it.)
I can't really comment on differences in attitude toward individual aircraft, but I would note that what seems a piffling degree of infringement assumes higher significance if that infringement takes place very close to a final approach track. Over the past few years we have lost important pieces of the CTA to the G.A. fraternity therefore almost any infringement is important to us.
Good points also from EGCC Rwy24. The original story is rather suspect to say the least. Mind you, there's nothing new in a bit of ATCO bashing - we should be used to it by now.