Japan doesn't do potatoes but corn on pizza is popular. I'm willing to tolerate a lot of different toppings but for some reason corn just seems wrong to me
Absolutely not. Granted, my country is right next to Italy, but I've only ever heard about spaghetti with ketchup on the internet, from people from other countries.
I grew up with a lot of Italian cooking and when I first went to Japan I saw a small pile of spaghetti in one of the bento lunch boxes covered with what I thought was marinara sauce. When I ate it and it turned out to be ketchup I almost spit it on the floor in shock.
Interesting...it is extremely normal in all the Scandinavian countries, and I've encountered it a lot in Germany and Netherlands as well. I never thought it was considered strange. I ate it a lot as a kid 30 years ago.