Off the top of my head:
India:
Sugar
Pepper
Basil
Mangoes
Bananas
Ginger
(Ceylon) Cinnamon
SEA:
(Cassia) Cinnamon
Mace
Nutmeg
Oranges
Lemons
Limes
Central Asia:
Apples
Carrots (Afghanistan, could be considered MENA or India but the MENA category is too OP)
East Asia:
Peaches
Soy Sauce
Ketchup
Soy sauce
Sesame oil
Africa:
Coffee
Coca-Cola
Palm oil
Americas:
Chocolate
Vanilla
Blueberries
Potatoes
Tomatoes
Corn
Pineapple
Strawberries
You definitely need "there are no rules" at first, but when your protege starts belting out Wonderwall in his best Bob Dylan impression, you have to switch to "there are some rules."
Where I live, if you order a random taco off of a delivery service (I know, I know, I've pretty much stopped), you have a decent chance of your "taco" being on a fajita shell and containing iceberg lettuce, with a packet of mass-produced hot sauce on the side if you're feeling adventurous. I think the weird absolutist positions well-meaning americans take is in response to this sort of disrespect for the history, the person making the food, the person delivering the food and the person eating the food.
Yeah I'm talking about people learning to cook for themselves. If I invite you over for pizza, you're gonna be bewildered if I give you butter chicken with naan. If I order pad thai, I'm gonna be mad if I get served a burger. Give me tea and call it coffee? No.
But say I was served tacos al pastor and I wanted to make some myself because they were soooo good? But the store only has hard shell tortillas? And Im not actually a big fan of cilantro, and I like my salsa mild? I'm still challenging myself, exploring other ways of cooking exploring other cultures, showing my appreciation for them and learning to respect them.