Empty tables and booths doesn't mean they can be used for customers. Im guessing that they were understaffed. Wait staff are assigned certain sections, or groups of seats, so perhaps someone called off, or there was an unexpected rush. Either way, seating people in those seats wouldn't have helped anyone, it wasn't intentionally done to ruin your dinner.
I think you want to write this as a review or contact the restaurant this is a crowdsource question page.
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