Why we need music in preschool

I watch this and wonder why its ok to have kids not have music classes until they are seven years old. We should ensure quality music for all children ages 2+. This kid certainly has the support at home.

I read today that something like 30% of children have NO books in the home. Some due to ignorance, but most due to cost. So many children go without. How many 4 year old ukelele prodigies are we missing?