If you play jazz, then you play with your fingers. If you're playing rock, you use a pick. There's really no rhyme or reason to that other than that's just the way it has been.
A woman should say: 'Have I made him happy? Is he satisfied? Does he love me more than he loved me before? Is he likely to go to bed with another woman?' If he does, then it's the wife's fault because she is not trying to make him happy.
If you are a gun manufacturer, the product you make is not subject to safety regulation by the Consumer Product Safety Commission. Toy guns are subject to safety regulation; water pistols are, but not real guns.