These radios do have a neat purpose. Two young female friends speaking house to house by radio describing intimate deatils of boyfriends, school activities, etc. The good news is, on flat land with lots of buildings you cannot expect your transmissions to go reliably beyond a half to three quarters of a mile. If you are camping on a 3800 foot mountain however your little family radio can be heard for tens of miles. The range of these radios is determined by the line of site rule and height of the antenna.
Height means more than the low one half watt of output power the radios produce.
It is up to you to tell your children what to expect when the radios are used. It is up to you to tell them they can or should not talk to strangers. In most cases other families will simply be curious who their camping neighbors are. There are immature youngsters that do use foul language and harass others, but most other people who try to call you and talk do so simply out of curiosity. Whether you answer or not is a decision you have to make.