Healthcare interoperability is usually framed as a standards adoption problem, and standards adoption is the easier half. Two systems can exchange perfectly valid FHIR resources and still fail to produce a usable combined record, because the same clinical concept was coded differently, captured at a different point in the workflow, or attached to a patient identity that cannot be reconciled across organisations.
The consequence is that integration programmes deliver technically successful exchanges that clinicians do not trust and therefore do not use — reverting to phone calls and re-testing, which is the outcome the programme existed to remove.