S&C alone >>

yes, there will literally never be another artist like her in japan. she writes and produces all of her songs, most of which have been acclaimed, and has full control over her career. she never once had to resort to shock factor.

Well, she lives in London

Something America has yet to achieve....

I think he means Ayumi is bigger in terms of total sales in Japan (albums+singles):

Ayumi: 53m
Utada: 36m

And the figures only include physical copies, digital sales not counted

The situation is similar to Madonna vs Whitney. Whitney had a bigger peak and higher average album sales, but Madonna is bigger overall due to higher total album sales:

Madonna: 200m
Whitney: 140-150m

Madonna has like 12-13 albums compared to Whitney's 7-8 too.