"The pitch is kiiiiiind of close, but that's about it. Different cadence, different levels of vocal fry, slightly different accent if you pay close attention. Johansson drops Ts for Ds pretty frequently, Sky pronounces Ts pretty sharply. A linguist could probably break it down better than me and identify the different regions involved."
https://old.reddit.com/r/singularity/comments/1cx24sy/vocal_...
There is also a faction claiming that Sky's voice is more similar to Rashida Jones's than Scarlett Johansson's:
https://old.reddit.com/r/ChatGPT/comments/1cx9t8b/vocal_comp...
This would mean that a celebrity could possess a voice similar to 0.5 million to 5 million other women, and potentially claim royalties if their voice is used.
I think people thinks others sound same not because they're similar from beginning, but because voices must homogenize under peer pressures. There's a proverb "nails that sticks out gets hammered". Most people probably has hammered flat voices intended to not stand out.