Meaning of permitting unauthorized minor to drive?

how is it that a 17 year old without a drivers license not be charged for that offense or the guardian be charged with permitting unauthorized minor to drive? the 17yo has been caught and charged for dui, mip but never no drivers license or the guardian was never charged. but the 15 year old was charged with no drivers license and the guardian was charged with permitting unauthorized minor to drive. the 15 year old was not drinking and only gave a friend a ride home. how is this?