I hear you--even within a hospital system, and even where standards exist, it's a pain. Ultrasound machines (for those that aren't imaging informaticists) are supposed to speak DICOM, but some do it creatively--one technically sent DICOM messages over the network, but most of what they contained was wrapped inside a proprietary XML blob rather than standard DICOM fields. What standard fields were implemented were implemented strangely, waffling between spelling out measurements ("centimeters") or using their abbreviations, mixing case, and reporting measurements to absurd precision (dozens of zeroes after the decimal point, for a bone measured in millimeters).
Sharing charts between hospitals is a mire of politics. There's the government's own Direct standard, which they mandated every hospital use to send charts, without any indication of what the recipient is supposed to do--a lot pipe them to /dev/null, because the vaguely defined content of the message is often useless and redundant with existing methods of communication. They're now working on legalese to require that you "do something" with the messages you receive, but exactly what that is (and how to objectively prove that you did it) they're still figuring out.
Then there are organizations like Commonwell, trying to monetize a data-sharing "standard" not even their founding members could be bothered to implement. They haven't sent a single chart as far as I know, but that doesn't stop them from issuing press releases praising their "interoperability" with the same frequency AT&T issues press releases praising their gigabit fiber.
Then there are HISPs (centralized, sometimes quasi-public, repositories of patient information). Some have managed to legislate themselves as mandatory middlemen, and, having done so, have proceeded to extract monopoly rents over the transmission of outdated and incorrect patient information. Even better is provider look-up--if they give you the wrong fax number for a physician, you are responsible for the HIPAA violation when a random gas station gets someone's medical information. This causes them to care as much as you'd expect about the integrity of the data they peddle (and that you're required to buy).
It's frustrating, because medical information has to be shared for it to be of use--there's no use having a mammography if no one will read the results, or if the people treating you can't access the study and have to order their own.