> Spanish is already mostly like this.

The word mostly in here is easily an overstatement... have you ever seen how semi-illiterate write Spanish? If you do, you will understand that there are lots of ambiguities in Spanish orthography. Almost any word can be written in many different ways and be read nearly the same. Moreover, the same symbol is often used for different sounds (but not for different phonemes). For example, the "n" in "cangrejo" and "no", or the two "d" in "dado".

Turkish is also mostly "WYRIWYP". We like to say that it's pronounced as it is written. As a rule, there are no exceptions in pronunciation, but there are some exceptions to that rule. :)

Dialects within the country and in Cyprus use the "Istanbul" Turkish for formal communication, so there exists only one "correct" way to spell each word. But of course, for casual talk and texting, each dialect writes certain words the way they pronounce them.

\* One cool corollary of the WYRIWYP rule is that there's only one correct spelling of any given sequence of sounds. If you take some native Turkish speakers and have them listen to a made-up word, 99% of them will come up with the same spelling independently of each other.

If your only points of reference are, say, English and French, Spanish might seem unusually phonetic, but most languages are written equally or more phonetically than Spanish is. English has had a long written tradition with lots of time for pronunciation to diverge from spelling without consistent or successful spelling reforms.

Many other languages haven't been written for long enough for these divergences to take place, or have had spelling reforms in the meantime.

Polish, for the most part: https://youtu.be/UUA1qrx6QB4?t=1m35s

German, or like mark twain said: "The only virtue of the language: After one short lesson in the alphabet, the student can tell how any German word is pronounced without having to ask;"

Thai largely is, although memorising the tone rules makes this rather more challenging.