“Mozart and Beethoven get performed worldwide more than any other single pop figure.”
We are not talking about single artists. We are talking about entire genre of music.
Go anywhere in the world. How many live classical music performances are there compared to live performances of popular music - fewer classical performances. The same is true for radio and TV and sales of recorded music.
As a genre, classsical music is simply not as “popular” as popular music in all its forms.
Live performances of classical music are harder to put together. If you don’t want to go by figures let’s go by the music itself. Famous Classical ‘tunes’ are better known than any single pop tune.