Through the years I've worked with several EHR, be helping their development be using it in my practice, and each had it's idiosyncrasies. In my country there was proposals by the government of integration, but as all things that need coordination, we're nowhere close to sharing information between care centers.

On a city we have several places controlled by the same entity, and they use an integrated EHR, so that a doctor who sees a patient at the emergency department has access to it's full history from the tertiary center, but at the same time the major tertiary/quaternary hospital isn't managed by that same entity and doesn't use the same EHR system, so we can't share information digitally. To make things worse, one system is made in Flash and all computers need to have an outdated Chrome version with the Flash plugin to run it. The other system is made in Java and some form of custom frontend framework, which works ok until it doesn't.

Expanding on this other system made in Java, it's a federal hospital, and we have other internal systems which doesn't communicate with this main EHR, so for example emitting radiology requests need us to copy paste information from two systems (like address, contact numbers), and on top of that those systems aren't connected to the national patient registry, and daily I have residents redoing requests to merge the information, otherwise the requests are made invalid.

I haven't touched on payments, imagine that each health insurance plan have different billings and we need to adapt the reality of what we did to what code better pays and input that in the system, so in practice the records are tailor fitted for each payment system, the actual procedure descriptions change, and we need to remember all that when billing and when treating the patient.

Add on top of that system outage and unreliability, and I haven't even touched much on the UI, which sometimes loses input text data or sometimes we have to input in certain fields order or else the system crashes, or the fact that the tabindex isn't set on all fields and we need to click with the mouse to go to a field.

Personally I've made a simple system for my private practice, while it doesn't have all the functionality, at least I'm the one to blame for it's particularities. I'm still exploring how to better input the clinical data, and I'm starting to think that general systems doesn't work. Each specialty has specific routines which need to be accommodated in the system, be it structured forms, be it clinical image input with annotations and commentary. The field is huge, and we're looking at how to design UX for immediate input and for later review, which sometimes are at odds (for example, a single textarea is easy to input, but how do we parse that data and present a timeline of clinical signs for example?).

I guess we need a Linux of the EHR, something which we can iterate on. I've looked into open source projects, but I don't know if the field is entrenched in inherent complexity or we're all trying to model too generic abstractions on top so that a small team of developers can't comprehend the system.

I should publish some code instead of rambling, but as the field is covered in regulations, I fear not even a code license can disclaim legal obligations.