It can't remove road film and the kind of greasy/oily contamination cars pick up on the road.
If you're using it for loose surface dirt, on a sealed/waxed car, washed regularly and driven little, it's OK.
Using baby shampoo is one of the great detailing red herrings. It is pH neutral, so it doesn't strip wax/sealant (hence the reason why people started using it) but it cleans far less effectively than an automotive shampoo should.
It is great for babies though - I wouldn't use a decent car shampoo on a baby because it will remove natural oils from their hair etc. Baby shampoos are designed to leave half the oils/grease in for moisturising/conditioning reasons!