Maybe like MacDonald's they are trying to upsell.
I am assuming that they have some sort of reserve quota that is set aside for emergency needy cases. If that is the case, it should be handled in the appropriate manner. I am sure that the nurses don't get any incentive for the upgrades but this is not right way. Car rental companies when they do not have the reserved model available, it is an automatic upgrade to a higher model at the same reserve price. Thats how you manage the inventory and keep customers happy. The same with hotel accommodation.
With these kind of encounters, the PAP then wonders why we complain a lot. Maybe they should start looking at how things are done on the ground. If there were no social media, the Malay chick trying to rent a stall at Tampines Mall would not have made the news.