Electronic medical records are a lot more complicated than getting data in/out of a system. You also need alerts for new data, query mechanisms, prescription writing, ordering, trending, etc. All all of that functionality needs to be available through a fast and usable UI. None of that is impossible, there are a lot of EMR / EHR products, but building everything and getting all the details right is a huge development effort.

Then if you want to share data across multiple organizations it's an even higher level of complexity. Industry organizations like HL7, HITSP, IHE, and CCHIT are doing good work to decrease interoperability costs. But we're still far from being able to build plug-and-play systems across the whole industry. The US has no central registry of healthcare provider organizations, so in general if you need data on a particular patient you won't even know who to query. And to even be allowed to electronically connect to another organization you need to have a legal contract in place first, either directly or through an umbrella organization.

The good-old-boys network isn't (much) of a problem in healthcare informatics. The real problems are irreducible complexity and legal / political issues.