KIds at assemblies are bored. In field service, they are bored. So they send text messages. Big whoopdie-do, but hey, the WTS, control freaks that they are, can't have that now, can they?
Also, text messaging is a handy way for kids and parents to keep in touch, as are cell calls themselves. At a large gathering like a Convention, such devices can provide extra security as family members keep in touch. What's so bad about that?