The salt and butter regime relates to a time when coffee was coarser ground and brewed in a pot on the stove and people were predominantly farmers and a bit careful with their money->poor.
But it’s not as crazy as it sounds if you ask me.
You're missing the bit about being farmers, quite possibly with cows. That makes butter (home made, from your own herd) cheap and coffee (from halfway across the world, paid for in hard currency, highly processed and passing through multiple intermediaries) expensive.
Many things, but we do like coffee.
The salt and butter regime relates to a time when coffee was coarser ground and brewed in a pot on the stove and people were predominantly farmers and a bit careful with their money->poor.
But it’s not as crazy as it sounds if you ask me.