All of your slash examples represent either–or situations. A swich turns it on or off, the situation is a win in the first outcome or a win in the second outcome, etc.
It's true that key–value store shouldn't be written with a hyphen. It should be written with an en dash, which is used "to contrast values or illustrate a relationship between two things [... e.g.] Mother–daughter relationship"
No, they don't. A master/slave configuration (of hard drives, for example) involves two things. I specifically included it to head off the exact objection you're raising.
"...the slash is now used to represent division and fractions, as a date separator, in between multiple alternative or related terms"
-Wikipedia
And what is a key/value store? A store of related terms.
And if you had a system that only allowed a finite collection of key values, where might you put them? A key-value store.
Still not sure what point you're trying to make. You attempted to correct GP's usage of "key-value store" and I merely pointed out that it is the widely accepted term for what is being discussed.
Whether or not it's semantically "correct" because of usage of hyphen vs slash is irrelevant to that point.