Don't choose to live in the temperate latitudes.  An hypothesis links the distance from the equator with the outbreak of food intolerances.
Products with evocative names like 'Healtheries' Kidscare come to the rescue.  Apart from carbohydrate they are very scarce on nurtrients, are like buying a whole 20g of hot air, which makes them highly priced. They are made in China from a long list of odds and ends.
Wholesome food is rejected and substituted with strange concoctions, more bizarre than Potato stix, costing twice as much, and accepted as healthy alternatives. Good plain food can't be all bad or can it?
I'd be the first to admit that some aspects of children remain a very curious mystery beyond me, and surely they can be demanding and active in a way that doesn't fit in with our chosen lifestyle.  It takes parenting and more allowances made for their behaviour along with acceptance that they can't all be a genius without labelling them with an abnormality and drugged-up en masse.  But, I'm still in the 18th century.