Here's a sad story from Canada where a driver's texting with her boyfriend led her to crash. Sure, he didn't make her read the texts and he didn't make her answer, but the fact is that she crashed into the back of a truck because she couldn't resist her boyfriend's texts.
We put all the pressure on the driver to resist texts - what if the boyfriend's first text said "R U Driving? Don't TXT." Still texting, still distracting, but the non-driving partner-in-texting should take some responsibility, too. Take a stand, make a pact with your loved ones - "Don't answer my texts if you are driving."
Even when the boyfriend didn't hear back from the driver, he sent more texts to her which, had she still been driving, would have caused more distraction.
If a friend doesn't text you back - assume he or she is DRIVING, not mad at you.