It was mandated because, in some cases, getting data from the patient is actually harmful. A CT scan is not benign. So to ensure that CT scans from manufacturer A could be read on a review station of manufacturer B, the DICOM standard was created.

But there is a real health element to it. Although I perfectly agree that standards are good for the consumer, the incentives here are not as strong.

I know nothing about IT project management for healthcare, but just the other day over here in the local news there was a mention that the all-singing-all-dancing healthcare application that the region (with ~1M inhabitants) has been spending years and around 800 million euros to get into production has been so poorly received that they're considering starting over from scratch. I'm so happy seeing my tax money well spent...

This is an implementation of something called MUMPS, which is apparently some US system that is very arcane but widely used.

Again, I'm not an expert on this topic, but it indeed seems like standards, API's, file formats and whatnot would be keys to a system where decoupled components can be evolved step-by-step over time instead of the current system which seems to be a humongous monolith.