My phone has a Drive Mode app. When activated, it turns off all non-voice functions when moving at above a certain speed. Of course, you have to have it installed and turned on to be useful.
Plenty of people only use text because on some plans, it's cheaper than voice options. Especially in the poorer countries. There, text is a major part of communication.
"I'm planning to live forever. So far, that's working perfectly." Steven Wright
"It is the duty of the writers to seduce me into suspending my disbelief!" Paul Beardsley