French was at some point written more akin to spoken, with variations in-between writers (and sometimes in text too).

Now the orthography is hard mainly due to: (1) change in the language not reflected in the writing, (2) etymological speeling choices made on standardization and (3) latent phonological information.

Instances of (1) include graphemes likes "au" [o].

Example of (2) is "pied" with final letter here to refer to Greek "podo".

Point (3) is more complex. Take "parent" were final t is mute. Its presence makes is clear it’s related to "parental". Some with pairs like "grand" / "grande" were in the feminine form the final d is pronounced.

Edit: Tibetan alphabet is notoriously difficult, and Thai alphabet is quite hard too, so the problem exists elsewhere as well even when staying in the realm of alphabets.