Well, if some people need a nanny, and most don't, how do you make those who need a nanny to buy the version of the product that has the nanny? Either you force everyone to get the nanny version (heavy-handed, especially to those who don't need it), or you rely on people who need the nanny version getting it (which only helps those who can admit that they have a problem).
The only other alternative is something like having some objective event trigger a legal requirement to have the nanny version. For example, a driving-while-texting ticket could trigger a legal requirement to have the nanny version of a phone that won't text while you're in a car.
