2 more (inter-related) reasons for more camber on front:
1. Front gets higher lateral load because most of the weight is on the front axle. This means more sidewall flex under corner load, and a larger compensation angle through camber is required
2. FWD tends to understeer - you are trying even out grip levels front and rear. Actually not just FWD, check out the camber front and rear of V8s and F1 - all have more on front.