Why was it empty?

She probably arrived shortly after they opened, without a reservation. Comments are calling her out in a big way, thankfully.

If that's the case, I bet if she were to come back in half an hour, all those "empty tables" would be filled by people who had made reservations.

EDIT: Hahahaha.

Dear Mrs. Williams,
Please accept our deepest apologies for the disappointment you encountered tonight.
Unfortunately, our rooftop bar was indeed fully booked and the only unoccupied tables you saw belonged to our gourmet restaurant, L’Oiseau Blanc, which was fully reserved.

Why was it empty?

She probably arrived shortly after they opened, without a reservation. Comments are calling her out in a big way, thankfully.

If that's the case, I bet if she were to come back in half an hour, all those "empty tables" would be filled by people who had made reservations.