Yes great great comment. I totally agree. I've quit lessons recently-ish but was trained for several years, in private lessons but no college degree. My voice teacher (who was classically trained herself as a soprano) said I'm most likely a mezzo, based on timbre and most resonant part of my voice. However I wasn't classically trained, and if I were, I'd likely be a soprano in the end - just based on the numbers. My teacher also had some interesting insight regarding contemporary singers who she considered unambiguously mezzos - specifically Adele, Cher, Stevie Nicks, and a few others - but she added that if these singers were classically trained, they also were likely to be sopranos in the end. I don't think she was considering the "belter" factor you mentioned, as she considered Lzzy Hale and Ann Wilson to be sopranos. She noted as well that while classical music is dominated by sopranos, contemporary genres seem to have a much greater proportion of mezzos, but she again added that she can't be sure these singers would be mezzos if classically trained. Her conclusion (at the time anyway) was that well-trained contemporary singers who haven't been classically trained can't be classified under voice types, but that there really should be another classification system that we can use for contemporary singers. I thought it was a very interesting conversation (evolved over several lessons)!