Heinzerling and Ackerman claim that misuses of economic analysis are the key explanation:

Most states, and many cities and towns, are deciding whether to do something to prevent these accidents. Some places have banned cell phone use while driving. Others have used laws already on the books — even homicide laws — to try to get at the problem.

Some of the country's most influential economists, however — based on research conducted with the help of generous funding from wireless providers — have concluded these restrictions are a bad idea. Why? Because the people who are talking while driving are willing to pay a lot to talk on the phone — more than many people who face deadly risks are willing to pay to avoid the risk of being killed. What these researchers have done is compare the price of phone calls made while driving with the "price" of deadly risks. Since risk is not, like cell phones and calling plans, directly bought and sold in the marketplace, economists have tried to find places where it is sold indirectly. (emphasis added)

By comparing the price of cell phone use with [an imputed] "price" of risky work, economists have concluded that banning cell phone use in cars makes no economic sense. The technique of translating lives into dollars is complex, but the bottom line of the cell phone studies is simple to state: the Cheryl Chadwicks of the world can go on talking into their cell phones while driving their Mercedes-Benzes, even though it means that quite a few of the Mariya Diments and Liya Murkeses of the world end up in the morgue. All based, amazingly enough, on the price of someone else's phone call.

I don't know if this is one of the studies (I can't find any acknowledgment of industry funding in the document), but I have a sense it gives the flavor of the genre. Heinzerling and Ackerman raise several broad challenges to cost-benefit analysis in general and its prevalence in the cell-phone discourse in particular. I agree with their moral objection to permitting the buying power of cell phone users to outweigh poorer individuals' interests in life. Perhaps "groups of workers doing dangerous jobs are paid, on average, a total of about $5–6 million more, per work-related death"--but my guess is that most of us would need to be compensated much more for accepting a similar risk of death via the negligence of a cell phone user. The first figure is based on work, which one needs to do to earn a living; the second is a risk that can easily be avoided.

Admittedly, some countries have overestimated the risks of cell phone use based on rumors that the gadgets "fry your brain." But it appears that we have a regulatory system that systematically biases us against reasonable precautions via highly artificial assessments of risk.