I’m sure it’s been done before, but imagine a Unicode with “case unification”.

What do you mean, “A” and “a” are different characters? They’re both the same letter of your alphabet. I guess we can add an “uppercase variation selector” if you really need to make both versions available, but this “case” notion is really a niche thing only used in certain scripts. Why would we waste space encoding it?

(Context: https://en.wikipedia.org/wiki/Han_unification )