There are two different concepts you are asking about.
How to enforce Role-Based-Access-Control with FHIR. This is not a part of FHIR, and even SMART leaves the POLICY and how one executes the POLICY out of scope. This may be frustrating, but it is the right position overall. This because every organization, region, and galactic enterprise will have different policies. Thus we must not bake a specific policy into the specification, but rather we strive to enable all possible reasonable policies to be implemented using a reasonable set of technologies.
How do I know if a given provider has some relationship with a given FHIR Resource. This is more of a question of how the FHIR resource model supports relationships. This too might end up being less satisfying to you, as there are many ways this is done.
The primary focus of those modeling FHIR today is more on how does one indicate the Agent role that an Agent has with a Resource. This is more a focus on how do I keep records if I want to keep perfect records. However you are on the other side of this perspective. Thus if the records are not kept perfect, then you don't have a linkage. The only solution is that you must understand the records keeping policy for the environment you are operating within. If that policy says that all resources created must have an author, then you can be sure there will always be an author. For any resource that doesn't have an author element, this would mean that a Provenance record would need to have been created. See Provenance, and the relationship to records-keeping thus the W5 report.
The PractitionerRole resource was added right before the STU3, and thus not all workgroups got a chance to integrate it. Thus this is a known breakage in STU3. Not all current build have rectified this either. These are the expected growing-pains that FHIR is going to experience during it's awkward years (in middle school right).... Which likely means that the workgroups could benefit from you submitting a CR when you see a clear PractitionerRole need..