Speaking as someone who doesn’t have children, It amazes me that a midday meal isn’t part and parcel of attending school.
It just seems logical that making sure there’s at least one decent meal not only helps from a health point of view but also has other benefits.
Healthy, and properly fed, tends to have mental, as well as physical benefits.
As has already been mentioned, it also removes any chance of the sort of stigma I remember when kids had to put their hands up if they were entitled to free meals.