They spent £1bn on Horizon, this isn't a case of not spending enough money. You might be onto something re:business fit - the system was designed to process be

They spent £1bn on Horizon, this isn't a case of not spending enough money. You might be onto something re:business fit - the system was designed to process benefits payments and, when the Post Office lost this work, was repurposed into an all-functioning EPOS (which it wasn't originally designed for). I get the distinct impression that, from the offset, the Post Office might have been more concerned with saving face and justifying the amount spent on the system, and this lead to a culture where none of the system's flaws (or poor fit) could be properly acknowledged or addressed.