In short, healthcare is very complex and there is no incentive structure that prevents the software from managing that complexity poorly, primarily because the users of the software are often not the ones making the purchasing decisions. Many are optimized for billing, and others are optimized for health systems who want lots of data points and jam the software with data collection forms.

There's lots of _better_ healthcare software out there. It's still complex, while remaining fairly user-friendly, but it tends to live inside healthcare startups and healthcare tech, and not deployed as broadly as the big EMRs like Epic, Cerner, eClinicalWorks, etc. These established players tend to be the only ones with the feature sets that big hospitals and health systems want/need.

Aside:

A lot of people in this thread are complaining about "regulations" making things difficult, but HIPAA, HITRUST, Meaningful Use/Promoting Interoperability, SCRIPT, etc. are not _why_ EMRs suck. They make it harder to start from scratch, but they do not prevent you from building easy-to-use software. The software sucks because there's generally no incentive to make it not suck and a whole lot of legacy suckage with a lot of momentum, money, and influence.