Nothing illustrates the depressing inability of humans to act cooperatively in the interest of the general good quite so clearly as the matter of cruise ship deck chairs.
Every cruise ship has enough deck chairs for all the passengers who might want to sit around the pool at any given time. And every cruise ship asks passengers not to leave towels and personal belonging on chairs in an attempt to reserve them while they are elsewhere.
If everyone would comply, there would be no shortage of deck chairs. But they will not.