This is correct as long as you restrict your point of view only to sets. Even in pure mathematics one is usually interested in sets with additional structures.

This is correct as long as you restrict your point of view only to sets. Even in pure mathematics one is usually interested in sets with additional structures. For instance, even though one speaks of the "set of real numbers" one usually implies that there is extra structure. In particular one usually requires that this set has operations "addition" and "multiplication" that make this set a ring. Then zero is the neutral element of addition and the annihilator of multiplication, so very special indeed!