Just make your one regular base curry. The spiciness is adjusted by how much chilis you add to the final dish. So to make a spicy batch, sauce some Thai chilis until fragrant then add your curry. That way you can designate spiciness by how many chilis you add.
I don’t get it either. The chicken sandwich is OK at best. A solid 7/10 just for consistency. Everything else is meh. People seem to like their fry sauce, which is probably required to eat their flat tasting waffles fries.
Americans like sauces and dressings on things. Ranch on everything, unless it comes with their own sauce.
I’m gen x and find that this transition started happening earlier. Once online smut was accessible in early 90’s, what little sex shown on the silver screen became less sought after and just became something we had to sit through awkwardly with family.