"You speak what you see" does not mean that every letter or combination of consonants is pronounced the same, but that there are clear rules that determine how every thing is spoken (with exceptions being rare). The fact that "ch" is pronounced differently depending on the vowel before is a consistent rule. In contrast in languages like english you do not have consistent rules like that for a big part of the language, to the extent that a native speaker encountering a new word (eg a street or town name) may not know how to speak or write it.