“Technology got us into this situation. Technology will get us out,” she said. However, she added, “We’re so afraid to tell people what they should do that you can kind of get away with murder under these conditions.”

Generally, companies have taken the position that text-blocking technology is embryonic and unreliable. They argue that they cannot shut down a driver’s service without the potential of mistakenly shutting off a passenger’s phone or that of someone riding on a train or bus.

Instead, companies have taken the approach of simultaneously warning and enabling, a mixed message that underscores a complex swirl of economic, technological and social factors. Perhaps the most pointed question is this: Even if the technology worked to perfection, would people accept having their service blocked? After all, the idea of mobile phone service is to let people communicate on the go.

David Teater, formerly of the National Safety Council and now a private consultant on road safety, who lost his own son to a distracted driver, said companies clearly feared the consequences of cutting off service for their paying customers. It’s an industry, he said, in which one of the most frightening words is “churn” — meaning the loss of a customer to a competitor.

“If you’re at Apple or you’re at Samsung, do you want to be the first to block texting and driving?” he said. “A customer might say, ‘If Apple does it, then my next phone is a Samsung.’”

But to Mr. Teater, that’s just an excuse. “If Apple had deployed this technology 10 years ago, there would be more people alive today,” he said. “Think about it from a parent’s perspective: How would you feel knowing Apple had the ability to prevent your teen from ever texting and driving, and they chose not to?”

Apple’s Lockout Patent

In the Apple case in Texas, lawyers who brought the suit had unearthed a fascinating document: a patent filing that Apple made in 2008, which the lawyers said was granted in 2014, for technology that would “lock out” a driver’s phone by using sensors to determine if the phone was moving and in use by a driver. If so, it would prevent certain functions, like texting.