Industry analysts also question whether cameras are needed on smaller, entry-level class cars with better rearview visibility.
"It may just be a couple hundred dollars, but it can grow pretty significantly if you are talking about ... an inexpensive car that was not originally conceived to have all these electronics and was only going to have a simple car stereo," said Roger Lanctot, an automotive technology specialist.
Before the delays, all new passenger vehicles were to carry cameras and video displays by September 2014. The industry has now asked for two more years after the final rules are published to reach full compliance.
Despite its resistance, the industry on its own has been installing rearview cameras, a feature first popularized two decades ago in Japan and standard on nearly 70 percent of new cars produced there this year. In the United States, 44 percent of 2012 models came with rear cameras standard, and 27 percent had them as options, according to the automotive research firm Edmunds.
Nine in 10 new cars had console screens available, according to market research firm iSuppli, which would put the price of adding a camera on the low end of the NHTSA's estimates.
These backing crashes are hardly a new phenomenon. Emergency room doctors, the National Centers for Disease Control and Prevention and the NHTSA have produced dozens of papers on the problem since the 1980s.
Researchers at the University of California, Irvine, started looking into the issue in the 1990s after noticing toddlers showing up in hospital databases of injured child pedestrians. They found that many of those children had been killed or hurt by vehicles backing out of home driveways.
In 1993, the NHTSA sponsored several studies that noted the disproportionate effect of backup accidents on child victims. One report explored sensors and cameras as possible solutions, noting the accidents "involve slow closing speeds and, thus, may be preventable." Still another 1993 report estimated that 100 to 200 pedestrians are killed each year from backing crashes, most of them children.
Three years later, Dee Norton, a reporter at The Seattle Times, petitioned the NHTSA to require improved mirrors on smaller commercial trucks and vans after his 3-year-old grandson was killed by a diaper delivery truck that backed over him.
The NHTSA started looking into technology as a solution, but in one proposal — issued in November 2000 — it noted that sensors, cameras and monitors were still expensive and promised to later reevaluate the feasibility of such emerging technologies.
Adding to the scrutiny were studies by Consumer Reports magazine, which started measuring "blind zones" to determine how far away a toddler-sized traffic cone had to be before a driver looking though the rear window could see it. The research found an overall trend of worsening rear visibility — due in part to designs favoring small windows and high trunk lines, said Tom Mutchler, the magazine's automotive engineer.
"Cameras are basically the only technology that is going to let you see something right behind the bumper," he said.
With a growing body of research, better statistics and inaction by regulators, advocates such as Janette Fennell, president of a safety group called Kids and Cars, and Sally Greenberg, then with Consumers Union, turned to Congress for a solution.
In 2003, U.S. Rep. Peter King, R-New York, introduced the Cameron Gulbransen Kids and Cars Safety Act, named for a 2-year-old Long Island boy whose pediatrician father backed over him in their driveway. Five years later, it finally became law.
While no one doubts that cameras could help reduce deaths, they aren't regarded as a perfect solution either.
One recent study by a researcher at Oregon State University found that only one in five drivers used a rearview camera when it was available, but 88 percent of those who did avoided striking a child-sized decoy.