Even educated persons will struggle if their only source is paper, because a lot of the Latin words that Italian is rooted on, actually have very different pronounciations in English.
Also: GL, GH, GN, CH, CE/CI vs CA/CO/CU, double-consonants reinforcing the sound, etc etc...
It may be difficult to an anglophone, but I'd argue that the phonetic irregularities of English are much more of a problem to a learner. "though/tough/through" never happens in Italian.
On the default sounds: I think it's harder in english where the correct sound is not strictly connected to the letters you write the word with. I don't think it's a coincidence that spelling bees are a thing for the english language, but I never heard of one in Italy...
Sure, if you have no source to determine the pronunciation of a word, it's hard (as for any language), but once you learn the building blocks you don't strictly need to know the word to know the pronunciation (apart from the accent)