How do you write Š or Ž? Or Ш or Ж, Щ, Ю? Or Δ? Or ლ?
The short answer is that it's a mistake to read my comment as saying 7 segments per se in the usual figure-8 shape is universal to how brains comprehend writing. It's not. You can dig up counter examples all day because that wasn't my point.
My point was that for a given language, the writing system tends to evolve to the point where each glyph contains just enough distinguishing features to not confuse it with any other glyph. There is also selective pressure to reuse the same segments but in different combinations, rather than try and come up with wholly different lines for each glyph which can only be learned by rote memorization. The end result of these pressures is that any language will evolve towards its own version of a 7 segment display. Call it a k-segment display, where k is only slightly higher than log_2(the size of the alphabet). I don't know what the k segment display looks like for Cyrillic or Greek or whichever other alphabet you pulled the other glyphs from, but I'm sure one could be found.
It definitely exists for Korean, as the Korean alphabet was designed in the 19th century and the sub-letters are intentional. I mention this because one of your chosen examples is a Korean letter.
This is absolutely not true. If this happened, you would have a very bad writing system.
Human communication systems have tons of redundancy in. The actual regular alphabet used by English has tons more shapes and detail that you are accounting for, and it uses it incredibly inefficiently. You can create a huge number of additional letters using the shapes that the alphabet is using.
And this is a good thing. It adds redundancy, and it very specifically is not the case that "each glyp contains just enough distinguishing features to not confuse it with any other glyph" - in fact, it contains far more distinguishing features than you need! This is to allow you to recover the information when things are unclear. There is excess information encoded as a form of error correction.
This is true for writing systems, for language grammars, for vocabularies, for every part of human communication. We always over-specify, to allow for understanding even when the receiver misses out parts of the information.
1 bit of error correction for 5.6 bits of information sounds pretty good.
False, it was in 1443. https://www.korean.go.kr/hangeul/setting/002.html