Stick an RFID tag on every customer's posterior when they arrive at the restaurant. Bingo, now you can track which rear end is sitting where. Seriously though

Stick an RFID tag on every customer's posterior when they arrive at the restaurant. Bingo, now you can track which rear end is sitting where. Seriously though, there are some good options with RFID tags. Does it really have to be per chair, or could it be people per table? You could put an RFID chip on each menu (though the menu would need to be left at the table for the duration of the customer's visit, and you would always need to provide 1 menu per customer). If you didn't want to use menus then you could use something else instead, as long as you could RFID tag it. When you go into clothes store changing room you often get given a tag with a number on it. That tag number defines that number of clothing items you have taken into the changing room with you and it reduces theft. You could operate a similar system, but based on the customers sitting at the table. It won't tell you which seats are being sat on, but it will tell the occupancy per table.