It has more to do with conservative (and dating centuries back) language policies on the state level, than with the language evolution per se. Like in English, where the archaic spelling only approximately reflects the modern pronunciation (see English spelling reform)
As an opposite example - Russian has undergone multiple reforms, notably under Peter the Great and the Communists, dropping silent letters, simplifying spelling, etc. - see Reforms of Russian orthography Note that in both cases the sovereign had dictatorial-like powers to effect such a change, which had never been the case in Britain in the last few centuries.
What is peculiar to France is that, while L'Académie Française exercises strong authority over the language norms, it appears to be rather conservative in reforming it. It appears that the major reason for this is preserving etymological form of words, rather than to reflect the pronunciation (this might be challenging to a beginning learner, but perhaps advantageous to more advanced one - see also the remarks):
French orthography was already (more or less) fixed and (from a phonological point of view) outdated when its lexicography developed in the late 17th century and the Académie française was mandated to establish an "official" prescriptive norm. Still, there was already much debate at the time opposing the tenets of a traditional, etymological orthography, and supporting those of a reformed, phonological transcription of the language.
César-Pierre Richelet chose the latter (reformed) option when he published the first monolingual French dictionary in 1680, but the Académie chose to adhere firmly to tradition in the first edition of its dictionary (1694).
Various other attempts at simplification followed, culminating in the "rectifications" of 6 December 1990.1 Some more radical proposals also exist to simplify the existing writing system,2 but they still fail to gather interest.
The above mentioned reform of 1990 changed spelling of about 2000 words.
Among Romance languages, Spanish and Portuguese have undergone relatively recent spelling reforms:
Spanish
The Spanish Royal Academy (RAE) reformed the orthographical rules of Spanish from 1726 to 1815, resulting in most of the modern conventions. There have been initiatives since then to further reform the spelling of Spanish: from the mid-19th century, Andrés Bello succeeded in making his proposal official in several South American countries, but they later returned to the standard of the Spanish Royal Academy.
Portuguese
The Portuguese language began to be used regularly in documents and poetry around the 12th century. Unlike neighboring Romance languages that adopted formal orthographies by the 18th century, the Portuguese language did not have a uniform spelling standard until the 20th century. The formation of the Portuguese Republic in 1911 was motivation for the establishment of orthographic reform in Portugal and its overseas territories and colonies. Brazil would adopt an orthographic standard based on, but not identical to, the Portuguese standard a few decades later.
Italian was apparently codified as a written language much later, when the pronunciation was relatively close to the modern one, as discussed here.
Likewise, modern Romanian spelling has been established relatively recently.
Remark:
- Not that in the case of most languages mentioned above, there exist variation between the spelling conventions used in different countries where the language is spoken (France/Quebec, Spain/Latin America, Portugal/Brasil.)
- As an example of how spelling matters and influences our thinking: I have witnessed once several French adults gasp, as a child declared that Sandra est la mère de Cendrillon. The child correctly noticed the phonetic similarity, but was unaware of different (etymological) spelling.
