Considering that these are lyrics, see the usage of "he don't know" as something artistic or in some cases as slang. In the case of artistry, it would seem that he purposely uses "don't" because it flows better with "know" considering that they are both words with an o-sound, which "doesn't" does not have. Also, don't is 1 syllable whereas doesn't is 2 and that might have also factored into his decision to use "don't" instead. If you listen to some rap, you might hear slang like "you's/you is...".

It never fails to amazes me why learners find this so strange, this question comes up all the time. Songs have no obligation to be grammatically correct and In songs, syllables are like gold. 'Don't' is one syllable, 'doesn't' is two. 'Doesn't' would sound pretty rubbish in the rhythm of the song. There is a not insignificant minority of native speakers who do in fact do use 'he/she/it don't' in their daily speech. My parents are two such people. But it's considered non-standard, if you were to use it in formal or written English it would be out of place and considered incorrect.