Is this weird? Mexican-American can't read/write in Spanish, but can in English?

So I meet this guy who is Mexican-American, and he reads, writes, and speaks fluent English. BUT…he can only speak Spanish, not read or write in it.

Don’t they have the same alphabet? From what I’ve learned, Spanish is even more phonetic than English (telefono vs. telephone) and so I was wondering if you’ve heard of stuff like this before.