Concatenating JS doesn't make sense when you are site like Apple. They have a lot of mini sites that are quite different from each other e.g. Store, iPad, Home

Concatenating JS doesn't make sense when you are site like Apple. They have a lot of mini sites that are quite different from each other e.g. Store, iPad, Home Page, Support, Developer that you may access directly and which may have 90% of JS in common. So they trade off first load for subsequent visits.