Not only are there are tables with three legs, but also tables with a single support in the middle, and tables suspended from the ceiling. There are low tables, and high tables. Shelves can also have four support structures (note there's a lot of wiggle room in those two words) of approximately 1m. Such a definition would allow so many loopholes...
The government of Fluoridationia doesn't care about objects that are not legally tables. It will go to your house and charge you a license fee for your shelf-that-is-legally-a-table and ignore the flat round piece of wood you hanged from the ceiling.
