Unfortunately incentives in American healthcare for insurance companies and providers are often misaligned. For example, when a physician wants to offer a patient preventive treatments, insurance companies resist paying unless they believe that they'll benefit financially. And because insurance policies are typically renewed on an annual basis, there's little reason for an insurance company to pay for anything that takes longer than a year to take effect.
If there were policies that lasted longer than a year, maybe this dynamic could change; insurance companies would be less concerned about paying for treatments that’d benefit another insurance company if a policyholder switched plans. Until insurance companies have a way to mitigate this risk, American healthcare will likely remain almost completely reactive. But, both for the sake of patient health and cost savings, there also needs to be a focus on prevention.