It's just until early 1900s that a "nationalist" (SiKyeong Ju) decided to use the "phonetic alphabet" into a primary writing system and revamped the system to be focused on words to be identifiable, rather than following the pronunciation. hangul now is just like equivalent of using a modded Phonetics alphabet that made each words identifiable. It's not representing the actual pronunciation, nor the actual pronunciation of the word. That's also the reason why the hanja (= kanji or "Chinese characters" or whatever your country calls it) was around until late 90s.
If you think Korean grammar is crazy, It's all thanks to him.
I observed that English shares that quality with Korean, and English speakers are not even able to hear the difference between [pap̚] and [bap̚], making this an odd choice to exhibit as a "very big difference" which will, by its lack of representation in the writing system, confuse English-speaking Westerners. It's a difference they can't perceive; why would they be confused over the fact that two identical sounds are both written the same way?
(Also, for reference, we say "Chinese characters" because that's what every country calls them. Hanja is just the Korean reading of 漢字. Kanji is the Japanese reading of 漢字. 漢字 means "Chinese characters".)
To an anglophone ear, [paʔ] and [baʔ] are indistinguishable - we also care more about aspiration than voicing. So it's odd to describe this, in English, as "a very big difference that is implied".