I never butter sandwiches, and am not American. As a pp said, mayonnaise with some fillings, hummus with some, maybe a smear of olive oil or pesto with others...
Mmmm, all those sound lovely. I can certainly get their appeal. But I guess I had always thought of those as creative and delicious riffs on the basic universally accepted norm of butter in sandwiches
. Especially Americans with their mayonnaise. I thought that with their excellence at fast food they were just saying 'Hey! Here's a great way to switch up your usual sandwich!' I was gobsmacked to learn that they don't operate with butter as the anchoring reality of sandwiches (some butter is even called Anchor ffs
)