Bernadette Peters, Patti Lupone, and Audra McDonald, are all classified as mezzo-sopranos, I believe. Audra for sure.
I used to be more of an alto. Case in point, I just found a recording of myself singing "Movie In My Mind" from Miss Saigon. Besides the fact I was so nervous, and I was over-vibrattoing like a nutcase, because I had no mix and it is a soft song, I used my 'soprano' high voice - and man, did it suck! It was weak and yucky. When singing the lower stuff, it was fine.
A couple years later, I'm still untrained. And my mix still bites. And I've lost my belt. But I'm now a bonafide soprano. Apparently, if I train, I'd be a lovely lyric coloratura - we'll see what happens.
Anyway...
I remember when "Wonderful Town" came out, many people critisized Jennifer Westfeldt for having a "weak" soprano, when indeed, she simply has a soprano. The way it is supposed to sound. Lovely, lilting, and beautiful. It seems now that is someone was to write songs for classic sopranos, they have to be on the highest notes possible. There's no classic voice writing anymore. If you're an alto, you have to belt an E, and if you're soprano, you had better be able to sing High Ds or Es night after night in almost every song.
Bring back anything Rodgers and Hammerstein - let's see what happens.
In answer to the question, I don't think sopranos are scarce - there's just no writing for us anymore. It's either coloratura or nothing. So off we go to classical...and it doesn't look like I'll have a career in that!
Deet: Shira, I Love You!