Evacuating a city because of a bomb threat is more unbelievable than every single person being at home because its Christmas?
I don't understand how that works.
Cities do get evacuated for threats, when's the last time you saw every single person gone because of Christmas?
Because it's Batman. There has never been a situation where he had to evacuate the city. Because he knows he'll always stop the villain. Plus there's a prideship in Gotham. Some leave, but there will always be people willing to stay and defend the city. That's why it's unbelievable.