Anyone who wants to use the records to improve healthcare. There are plenty of these folks in the medical field, based on my time in medical school and brief stint in a medical research group.
I would also include anyone involved in your direct care, i.e. the front-desk personal at the various doctors offices we visit, who have no way of easily obtaining your medical history if you aren't already in their system.
https://www.hhs.gov/hipaa/for-professionals/faq/authorizatio...
When providers fail to obtain medical histories for new patients that's not due to any legal restrictions. In most cases they simply haven't bothered to implement the open interoperability industry standards which make it easy to exchange such data, or haven't joined networks that facilitate such exchange. For example, the majority of physicians still don't have a publicly listed DirectTrust Direct Secure Messaging address even though they could have one at a very low cost.
This is so nebulous. Anyone can claim they want to improve healthcare. The removal of abortion access has also been repeatedly been justified as improving healthcare. The Tuskeegee experiments (where they just let black men live with a curable, debilitating disease and continually lied to them about their suffering, some of them to their graves) was justified as improving healthcare. "Wanting to improve healthcare" does not preclude people from horrifically unethical behavior. Get better standards if you want to be accessing the private information of people without their consent.