One disadvantage of vertical integration is that the in-house provider may be too small relative to the efficient scale. Building contractors usually employ their own bricklayers and carpenters, but hire sub-contractors for electrical works and elevators. Large commercial buildings have their own teams of cleaners but hire external contractors for maintenance of heating, ventilation, and air-conditioning equipment. Consider the following practices of the Hong Kong medical profession. Doctors are not allowed to advertise.
Doctors can sell medicines from their clinics.
Until recently, they could dispense drugs in unmarked containers without indicating the medicine. At the time of writing, they were not required to mark the expiration date of the medicine. Doctors admitted in Ireland can practice freely in Hong Kong, but graduates of Harvard Medical School who are qualified in an American state must undergo special training and a rigorous examination.