Persons with a military or amateur radio background in the US of A use it.
Sigh, I guess I was making a bad tongue in cheek joke in which only I was laughing.
Of course military people use it around the world. It's not like I never heard it in the USA, it was more that if you're on a phone call with a call centre, in the UK or India or whereever interacts with the British public, it's all about the phonetic alphabet.
So if a person does this:
"S for Sugar, F for Freddy, B for Bertie..."
.
They read back to you, "So that's S for Sierra, F for Foxtrot and B for Beta" Probably by rules that they have to (with their cheat sheets next to their phone!).