that's ok if its one user or one specific group of users. but what happens when there are multiple branches of users all wanting different things from one system. what youve all described are simple silo databases and useful to that specific person or element.
When multiples all want different things and IT spend goes out the window cause billing need something in blue or red and clinicians want in green cause they dont like red, everything starts costing as work is rehashed and redone on the fly.
Medical and specifically the NHS system was destined to fail no matter how much money was thrown at it. as a single system that does appointments, Medical records, Stores, Billing, triage, Xray access, diagnosis and then prescribing and reporting as well as being user friendly to every user it will ever encounter (including the 80 year old receptionist whos been there since 1972 and only works on Tuesday mornings)and god knows what else the NHS do that i don't know about.
No matter how good you are postgresql or other freebee database wont do that any time soon without massive support programs.
It would be nice and simple to think thats what can be achieved on the cheap but not to run a hospital