Different strokes. In the Philippines, they eat mayo with their hot dogs. Probably because they couldn’t get ketchup during WWII. They also improvised at that time, and invented banana ketchup. Sound awful, except there are about 500 varieties of banana, and only a few of them taste like the bananas we get in our grocery stores. Some of them aren’t sweet at all.
I’ve had mayo on hot dogs in Chile. There is a pretty decent chain restaurant which focuses on hot dogs and myriad toppings including mayo - http://domino.cl
In Greece they put french fries in the gyros which I always thought was weird...