... and all Latin/Romance languages, English is the exception, Italian, Spanish, French, Portuguese and Romanian are all pronounced as they are written (or at the most with some always-the-same reading conventions).
?? I dont' quite follow what you're saying. The sound 'o' can be written in French in a lot of different ways, some of them even don't even have an 'o' in them ("au", "eau", "aux" "aux" and I probably forgot some). It's notoriously difficult to write things in French just because of the discrepancy between what you hear and what you should write.
Au in French is never pronounced as it is written (like augen in German or aulico in Italian), but always as a O
Once you know the rules it's pretty easy
Also French (like Italian, Spanish and others) have accents to help you decide how to pronounce a word
Now consider these popular examples of English inconsistencies
The bandage was wound around his leg to cover his wound.
The insurance on the invalid was invalid
I did not object to the object.
Not disagreeing with your overall point, most romance language have a much easier mapping from speaking -> writing than does english, but the principle of "write as you speak" is probably the simplest you can get.
(ie, the letter 'c' is used to represent different sounds in the word 'calambre', 'chorrizo', 'proyeccion'. It's not complicated to learn at all, but you still have a one -> many mapping on the letter -> sound. For languages like Serbian, it is straight up one to one.
Cane (dog) and cena (dinner) in Italian are two examples of soft and hard C that depend on which vowel follows the letter C.
It wasn't like that originally, Roman C sounded always like K, Caesar was pronounced Kaesar (German's Kaiser comes from it).
Than middle age came and things changed, but the pronunciation stayed consistent after that
C+a, C+o, C+u = hard C
C+e, C+i = soft C
So it's not simply about "what you write is what you get" but it's the rule that is consistently the same
Phonetically the examples above are unambiguous though
Soft c = voiceless postalover affricate
https://en.m.wikipedia.org/wiki/Voiceless_postalveolar_affri...
hard c = Voiceless velar plosive
https://en.m.wikipedia.org/wiki/Voiceless_velar_plosive
They are not exactly what you write, but they have precise phonetic symbols expressing how they sound (which is not always how they look on paper)
By convention, in French every time you find written: "au", "eau", "aux" "aux" you pronounce it "o".
If you hear "o", it may be "o" or any of the above.
There may be small "nuances" like with Z in some languages that can be hard or soft (there are anyway "coded" rules - not necessarily "simple" - but only a handful of exceptions), Italian:
http://www.attori.com/dizione/Diz11.htm
Now go to English and read aloud (say):
flier
plier
pier
tier
tire
It is true that if you happened to know French well, and you are familiar with the language writing conventions you can read the language just fine, but that's tautology.
Roughly half of the letters written in French are not pronounced, either because they come too soon in the word, or because they are followed by another letter or because they are too late in the word. Unless the next word starts with specific letter, in that case you do pronounce the ending of the previous word. Sure, for a native speaker it could be very easy to read and write, and it might be determined by very consistent set of few dozen rules, but I would say that reading or writing French is anything but straightforward.
When you have a language that's half nordic, half french, half german, with tons of words from elsewhere, the rules aren't really going to be rules. (there is of course a much more linguistically accurate way to say this)
Especially it's false in French with 17 different ways to write "e" or "o" even though it's spoken the same...
There is an excellent TEDx video where two linguists that are advocating for a reform of the French orthography invent a word and then write a script to list all the ways it can be spelled, following the existing rules of French spelling. The result is 240 ways to spell it.