As Thai language is a tonal language. The root language of Thai is Pali and Sanskrit not German or Roman so it made Thai alphabet much different. We don't have the system like Pinyin in Chinese. Therefore, when we pronounce a Thai word by English spelling, it's just an approximate sound. Just try to use English letter as close as possible to express the Thai tonal pronunciation.

long story make it short. because it's the root from pali & sanskrit.

pali is meaning keep the BUDDHA 84000 ITEM in our mind. And learn more. for instant the word KESA in Makatie written "เกสา" ( KE-SA) Sanskrit written "เกษา" ( KE-SA) Thai "ผม" (phom) English "hair" Japan "kami" but this is world language . PALI mean RUPA 44 this is elementary to start to learn pali of the BUDDHA.