 Sharp three-transitivity of Möbius transformations

For ordered triples of distinct points of the Riemann sphere, a unique Möbius transformation sends the first triple to the second. Normalize each triple to $0,1,\infty$ using $T_z(z)=(z-z_1)(z_2-z_3)/((z-z_3)(z_2-z_1))$, with the usual limits at infinity, and compose $T_w^{-1}\circ T_z$. Any two choices differ by a Möbius transformation fixing those three standard points. Fixing infinity makes it affine; fixing zero and one then makes it the identity. Thus the Möbius group action is sharply three-transitive, a stronger property than mere transitivity on triples.