Why so spell checkers suck?

Hmmm... who is this Ali G that you speak of???

The above translated (all courtesy of whoohoo.co.uk - The British Dialect Translator):

Yea' dat one makes me laugh.. he iz hactually da fe real brainiest geeza who graduated from cambridge university. he just made da success hof messin' wiv peeps.

Yeah that wahn makes me giraffe.. he is actually a 'eaven and 'ell intelligent geeza 'oo graduated from cambridge university. he just made a success of messin' wif people.

Yeah dat wan makes me laugh.. he is actually a really intelligent paddy who graduated from cambridge university. he jist made a success av messin' wi' people.

Yeah dat one makes me tuck.. he is actually a dead intelligent feller oo graduated from cambridge university. he juss made a success o' mess'n wi' people.

Yeah 'a' 'un mecs uz laugh.. he is actually eur chuffin' intelligent bloke whoa graduated fra cambridge university. he just made eur success o' messin wi' fowk.

Yeah that 'un makes me loff.. he is actually a really intelligent geezer who graduated frum cambridge yowniversitoy. he just med a success of messen with people.

Aye that yen makes wor laugh.. he is actually a deed intelligent blurk whe graduated from cambridge university. he just myed a success iv messin wi' people .

Yeah 'at a body makes me laugh.. he is actually a pure intelligent cheil fa graduated frae cambridge university. he jist gart a success ay messin' wi' fowk.

Yah that one makes myself laugh.. he is actually ah hairlairh intelligent chap whoh graduated mwah mwah sweetie cambridge Oxford. he fie made ah success of messing with old beans. Don't you know?

OK me duck.