Definitely not just a British thing. I have lived in 4 countries too, and have been in Italy for 24 years.
Italian children eat just as much junk food as other kids, trust me. And many Italian mothers will feed their kids pasta and tomato sauce every day of the week because it's what their kids like.
In restaurants children will be served their pasta and sauce first, while the adults dip into the antipasti. I've rarely seen childrens' menus, true, but that's because the parents will say "he'll have a bowl of pasta and sauce instead of...."
My dp was a chef in a tourist resort and it was very common for mothers to bring their own pasta and insist on cooking it themselves in the hotel kitchen.
A friend of mine wouldn't give her child spaghetti till she was about 10 because she was terrified she'd choke.
When dd was about 10 months old, she loved cauliflower. I was told she'd die a terrible death (virtually) because everyone knows children can't eat cauliflower till they're about 12.
She's now 14 and hasn't touched it since she was about 3 so I'd say to all the "my 11 month old eats everything" that that's great, but hubris can be a sobering thing, and the minute they realise they can say "no" then they'll start exercising the right to do so. 