Could it be?
Banning talking and texting on phones has no effect because people are doing it anyway? Maybe people that are most likely to do it are the ones that may be careless drivers anyway?
Here in Brazil, the same ban exists but I see people driving and using their phones every day. Only yesterday, I observed someone stopped in the middle of a narrow street, blocking traffic.
With three cars behind him he would glance into his rear view mirror when anyone blew their horn but kept talking and blocking the street anyway. He knew we were there but didn't care.
In a way, it was good that he at least stopped. Obviously, he was an arrogant person that didn't care about anyone else and might have been a bad driver without the phone.