I've done some consulting in the realm of medical software and while I don't know every major in-and-out, the real problem is the market.
Here's an example of bringing a piece of software to the medical market:
- Come up with the idea for some software, write, debug, document it. **This is not the problem**
- Find a hospital or clinic, meet with the board (3+ months wait) to see if you can petition it's doctors/nurses/whomever to use your software.
- Find a group of medical staff that is willing to use said software, free of charge, on the side. You probably have to 'pay' them to do it somehow - give it away for free, or discount, when you actually start selling the software, or just a lot of business lunches. These people cannot legally use your software for actual medical purposes. They're just doubling their workload by using your system next to whatever the current mechanism they use.
- 6+ months go by. Now it's time to approach the board of directors of the hospital - make a presentation with the recommendations of the software users
- Now, hire an independent software analyst to review your software, while working with a lawyer - who themselves will work with one or more of the hospital's lawyers - to ensure that you're following all the legal requirements and hopsital software requirements. 1-6 months before you're certified for that hospital.
- Unfortunately, there may be other requirements that supersede the hospital's individual requirements, usually municipal, state, federal regs. You'll need to get certified on these (0-3 years duration).
- Finally get it rolled out to the hospitals and sold in the wild (note: repeat the certification steps for each new hospital/hospital group, but they'll be expedited)
Okay, so that's the general process. One part software development, 82 parts legal wrangling, red tape, and butt kissing.
You're also not going to make this thing very open. You won't use public libraries, because they need to be certified. You won't have common data, because every hospital wants different things. You're not going to use new technology or standards because it takes years to get it live, and when you make changes like that you have to start over.
You're also not being paid to add the features to make this externally accessible to god knows what.
Imagine the extra requirements involved in providing legal access to medical records to third parties. It's not a technological barrier; it's almost all legal. They must be certified, the two must have a contract, etc, etc. You can't just give it to anyone who asks - you have to have a legal relationship with each asker. That will have to be signed off on by the board too. And so on, and so on.
The project I did some consulting on? They're basically a sort of spreadsheet with calculations. It's been ~4 years, and it's still bouncing around, not yet fully certified and ready to open for sale. If they went back and added 3'd party export functionality, it'd be another 4.