Why the U.S. has been slow to adopt coronavirus contact-tracing apps

For all the attention on Apple and Google's joint effort to help track COVID-19 exposure, adoption of the technology in the U.S. has been limited, especially compared to other countries.

Why it matters: The companies' exposure notification technology could augment the labor-intensive work of contact tracing that experts say is key to controlling the spread of a disease for which there is no treatment or cure.

• As NBC News reported Sunday, even some of the states that expressed support for the project have yet to move forward with apps, with others saying they have no plans to leverage the technology.

The big picture: There are several reasons adoption in the U.S. has been slow. As with many other aspects of addressing the coronavirus crisis, federal health authorities have left the choice whether and how to use exposure notification technology to individual states.

• Handling things at the state level forces each state to at least partially reinvent the wheel, all at a time when scarce tech resources are stretched thin.

Between the lines: It's unclear how many Americans would voluntarily use such apps, given a cultural aversion to government tracking as well as significant portions of the population who don't believe COVID-19 is a significant threat and refuse to wear masks or take other steps.

• That's despite the fact that Google and Apple have made the technology as simple and privacy-preserving as possible.

Go deeper: Apple, Google deliver test code for virus-exposure tracking