A very complex domain is medical records. The UK has managed to blow billions on custom systems that didn't work. The simplest thing that could have worked was

A very complex domain is medical records. The UK has managed to blow billions on custom systems that didn't work. The simplest thing that could have worked was maybe just to download an open source version of VistA (https://en.wikipedia.org/wiki/VistA https://en.wikipedia.org/wiki/VistA). Probably would have worked better.