the key does stop existing, insofar as referring to any name that is not defined in lua results in nil. which includes variables, since they are defined in a global table. i don't actually know what happens internally.
i think the most interesting design detail of lua tables is just glossed over as "nil-holes" in this article. namely, that nil values do not exist. there is no table.delete(key) method, you just zero out the value and the key stops existing. the same thing is true for any variable, if you set it to nil it ceases to be. i find that implementation fascinating.
the latest volvo is 1.98m wide. the underground garage at my last place had a 2.2m wide door which i once managed to clip in my chevy volt. i wonder if the auto-pilot or whatever is good enough to navigate that.
interesting! it should be equal since it's always just a pointer to that same table.