I find that really hard to believe having seen the state of most school dinners tbh.
Maybe if compared to some ideal school dinner designed by Jamie Cocking Oliver, but not when compared to the complete shit most kids are offered!
One of my DC was given a pizza slice with spaghetti hoops and sweetcorn followed by a chocolate chip cookie and glass of milk a few months ago FFS, apparently both spaghetti hoops and sweetcorn are portions of veg 
Whereas when I send a packed lunch it will be a sandwich (either cheese or some sort of veggie ham slices) on best of both type bread, or a slice of homemade pizza from the night before, or a home made veggie sausage roll. Plus a piece of fruit (usually satsuma or doughnut peach), some cucumber and carrot sticks, a few halved cherry tomatoes,
and some peas in the pod when in season. Then a no added sugar cereal bar (the sort that are made from oats and fruit only) and usually a packet of either mini cheddars or mini ritz crackers.
Fuck off telling me that's a lower quality meal than pizza with spaghetti hoops and sweetcorn!