Since we all get attached to possessions, I think smashing the phone made a point.
Unfortunately the parents should have (1) spoken with the daughter about this when she got the phone and had a firm agreement on texting (we did with our daughters), and (2) they should have monitored the phone bills more closely. My bet is this didn't ALL heppen inb one month - there undoubtedly was a ramp up.
And few in this area near Denver have commented on the fact that the girl's grades - and clearly, her attention to school - fell off as the texting increased. To me that's the primary concern.