Root cause.
When you buy from an ERP vendor, you are not just buying software, you are buying a logical model of an idealized corporation. If that model doesn't reflect your actual organization, you can try to customize the software, but beyond some threshold of mismatch, it's easier to change your accounting & control & governance processes to match the software.
SAP and Oracle are no different in this respect.
But almost none of the banks actually work like that, apart form some small insignificant shops which can't afford such customization. Each has some unique stuff that makes it better than most competition in that area. Behemoths of banking world run their pretty unique things, workflows, specific jurisdiction reporting etc. so each of them have more or less massive customization on top of basic common stuff.
I guess it goes without saying almost constant flow of changes, either from business or regulators keeps hefty IT teams busy to maintain that customization and ensure things keep working. Also logically the complexity has only one direction to go, and so it goes, slowly but surely.
I am not even sure if business properly realizes all this, maybe they do or maybe they are kept in continuous cloud of bullshit from IT managers who of course want to preserve their jobs and importance (headcount, impact) within corporation. Anyway the prospect of migration to something else is something they (rightly) detest and want to avoid if possible, since costs and duration are massive, potential issues tremendous and backbreaking, and there is absolutely no guarantee of success.
It definitely doesn't, as in the top directors likely don't. It is likely that they brought in some kind of consultant who sold them this solution to the higher ups against the protests of the lower managers
I managed a whole 8 months in a local government role (not UK) before jumping ship when I realized how futile trying to improve anything was
After we went live they thanked us for this, as it had forced them to rethink their processes, and they were pleased it had led them to much better and more optimized ways of working.
Each airline on-boarded would demand mandatory features that they couldn't do without. Keep in mind these features weren't free, they were billed market-rate development charges - though the company didn't make money off that, the core business model was usage-based billing.
More than 80% of implemented features would go completely unused.
Full on ERP would be a disaster.
Most of this I blame on the Sales People. They will promise anything to make the sale. Somehow part of the risk should be borne by the vendor.
When something gets 10 times more expensive than anticipated, there is some serious mismanagement and political 'death march' involved.
This longing for 'one system' is probably the fundamental problem. And these consultant firms with slick salespeople feeding on the procurers' dreams.
Besides the companies themselves constantly upselling you and having idiotic licensing terms. Both are very much the sort of companies with products you only are "able" to implement with extremely expensive outside consultants.
You have third-party consultants charging for addressing all the mistakes in the system, present on daily chats and constantly chasing them around for support. Oracle's always upselling you on the parts of the system you haven't implemented yet.
The actual municipal employees are making 75% (my own estimate) of what their industry peers make in salary so they're just trying to do their job as they found it, not attempt to replace the status quo with a "solved, open source, one-size-fits-all solution" like so many here believe various ERP systems are. Everything sounds better on paper.
It certainly is, here in the Netherlands consultancy companies are often directly mentioned as a cause for a lot similar projects going over budget. Though the government really doesn't seem to be able to do much about it or simply doesn't care. As most recently they appointed the ex vice-president of one of those companies as a state secretary of Digitalisation https://en.wikipedia.org/wiki/Zsolt_Szab%C3%B3_(Dutch_politi...
