That may be the case for English speakers, but it's not at all the case in Spanish. The usual spelling mistakes in Spanish are b/v (they sound exactly the same, so you just have to know which one is the correct spelling) j/g and s/z/c (which sound the same for most speakers) and knowing which words are written with "h" (which is silent). The only case where vowels are sometimes involved in spelling mistakes is with i/y, but it's much more rare than the other cases.And it is the vowels that tend to drift from dialect to dialect.In English, but not in Spanish. Spanish dialects don't really differ in the vowels, but they do in some consonants (c/z, s, ch, ll, rr, ...)