There are a few others, but they are mostly neighbours of Greek and Latin, or else motivated by them.
Writing systems using two separate cases are bicameral scripts. Languages that use the Latin, Cyrillic, Greek, Coptic, Armenian, Adlam, Varang Kshiti, Cherokee, and Osage scripts use letter cases in their written form as an aid to clarity. Other bicameral scripts, which are not used for any modern languages, are Old Hungarian, Glagolitic, and Deseret. The Georgian alphabet has several variants, and there were attempts to use them as different cases, but the modern written Georgian language does not distinguish case.
Now, of these, Cherokee, Osage, Deseret, Adlam, Varang Kshiti are recent scripts, that got the idea from Latin. That leaves us with:
- Cyrillic, whose lowercase is pretty half-hearted—they look just like the uppercase, and they’d have gotten the idea from Greek and/or Latin (Peter the Great) anyway.
- Coptic, Armenian, Georgian, Glagolitic, which are also immediate neighbours of Greek.
- Georgian used to be cased, and now isn’t. The uppercase and lowercase look different. (Meaning, they look authentic, originating in cursive.) EDIT: I was wrong: Georgian scripts – Wikipedia . The introduction of case, by mixing two historical variants of the script, was a shortlived innovation in the 1950s; historically Georgian was never cased.
- Armenian lowercase also looks different.
- Not sure how much case was used in Glagolitic.
- Coptic is now cased, but my impression from Googling is that casing is rare; Bicameral scripts speaks of “limited modern use”, and any facsimiles I’ve seen of Coptic were unicameral.
- Old Hungarian: if you read the fine print in Old Hungarian alphabet, not really cased, just makes the first letter of proper names slightly bigger. And Old Hungarian would presumably have gotten the idea from Greek or Latin as well.
So all the scripts that have case are either modern, and got the idea from Latin, or were neighbours of Greek. They developed case either at the same time as Greek and Latin (9th century), or later on.
The explanation is that case was a meme that originated in Latin and Greek, at the same time—independently or not, who can tell; it originated as a space compression technique associated with the high cost of parchment; and it spread out geographically from Greek to its cultural neighbours. It didn’t spread any further than Armenian and Coptic. Arabic and Syriac would have been next, and I don’t think their letter shapes would have made sense with case. Amharic would have made more sense I guess, but I don’t know how much cultural contact there was between Coptic and Amharic, and I don’t think casing was that prevalent in Coptic anyway.