I own both the books. AFAIK, "healthy" snacks mean snacks that are home made and nutritionally balanced, rather than our usual perception of snacks being processed, high-fat, high-sugar, high-salt crisps, cakes, biscuits, Gregg's sausage rolls, etc - which is what we want for all our kids, isn't it? And both the girls and boys Usborne books have a sweet treats section. I just read treat as something that nobody wanting a healthy diet should eat all day, every day - again, a sensible message for both boys and girls. Sadly, food can't just be food for children, because the British diet is, on the whole, dreadful, so you have to start early with a truly healthy eating message - everything in moderation.
I'm not claiming that for these books, like, but I do reject the notion that any cookbook for children containing healthy snacks and sweet treats is fast tracking them to an eating disorder - it's common sense. And balance.