Have just returned from the States last week. As an airline employee I travelled out in business, with my mother. On the way back my mother travelled back on a different day to me and no amount of extremely polite cajolling could persuade check-in or gate staff to allow an upgrade. The excuse given was that the club class section was catered to an exact number of booked passengers. When I fly to Man from LHR even with the barest minimum of passengers we always allow spare catering so I think porkies were being told here. My experience is that the Americans are much more likely to fall into the jobsworth camp with regard to upgrades than Europeans.