Why Are There So Few Contraltos?

A big part of the reason they are rare is because "contralto" typically refers to a pretty specific combination of range, color, and tessitura beyond other "general" voice types (by contrast, "soprano" can still represent a wide variety of timbres and tessituras through different sub-fachs).

How rare is being a contralto?

A contralto is a type of classical female singing voice whose vocal range is the lowest female voice type. The contralto's vocal range is fairly rare; similar to, but different from the alto, and almost identical to that of a countertenor.

Are Altos and Contraltos the same?

The terms alto and contralto are sometimes used interchangeably but it's not that simple. Alto, strictly speaking, refers to the vocal range one rung higher than a tenor. ... Contraltos, range-wise, fall between the mezzo and the tenor.