Greg Mankiw's Blog: The Pigovian Slippery Slope
The answers are:
Yes, really depended how much French people go to picnic and having baby; using hamper; when you inherited ancient picnic set, handling the set is more time consuming and costly; the power usage of dishwasher, detergence cost, hand wash and polishing them. We only use it about 4 or 5 times a year. Buying plastic much cheaper, I think, I don’t know what is the cost of plastic things are.
Disposable diapers, I don’t know what is cost of disposal diapers but I can guess; the washing cost of cotton; chemical and power costs of washing and drying and labor also.
Picnic hamper vs plastic set : cost= x+y+z
Disposable diapers vs cotton diapers: cost = x+y+z
Then we can see then whether they have externality, but benefit of this case is you can teach people awareness of clean environment from the cradled.